sexy information 🤑

الارشيف لـ فبراير 2015

السبت، 28 فبراير 2015

How to Scroll Top or Bottom of Document Using JavaScript

بواسطة: Unknown فبراير 28, 2015 أضف تعليق

There are different methods to scroll HTML document using JavaScript, You can scroll the document to Top, Bottom or in any part or to view any element in the document using JavaScript.

To scroll the document using JavaScript, there is a scrollTo() method in window object which takes the X and Y coordinates of a point and sets these as the scrollbar offsets.

The scrollTo() method scrolls the window so that the specified point is in the upper left corner of the view-port. If you specify a point that is too close to the bottom or too close to the right edge of the document, the browser will move it as close as possible to the upper left corner.

How to Scroll Bottom of Document Using JavaScript

You can use the following set of JavaScript codes that scroll the browser to the bottom most page of the document.

var documentHeight=documentElement.offsetHeight;
var viewportHeight=window.innerHeight;
window.scrollTo(0, documentHeight-viewportHeight);

Here the first variable documentHeight specifies the read only offsetHeight properties of any HTML element return its on screen height, in CSS pixels and the returned size include the element border and padding but not margin.

And the second variable, viewportHeight specifies the height of viewport, which is obtained from innerHeight property of window object.

You can execute this code on onclick event of JavaScript hyperlink or on onclik event of any button or text as given below.

function gobottom(){
var documentHeight=document.documentElement.offsetHeight;
var viewportHeight=window.innerHeight;
window.scrollTo(0,documentHeight-viewportHeight);
}

You can call this function gobottom() within HTML file as below.

<input type="button" value="Go To Bottom" onclick="gobottom();">

On the other way, you can execute onclick event of button with assigning a function on onload event of window as below.

<script>
window.onload=function(){
var bottom=document.getElementById('bottom');
bottom.onclick=function(){
var documentHeight=document.documentElement.offsetHeight;
var viewportHeight=window.innerHeight;
window.scrollTo(0,documentHeight-viewportHeight);}
</script>

You can call this function by placing id attribute within HTML file as below.

<input type="button" value="Go To Bottom" id="bottom">

Preview:

How to Scroll Top of Document Using JavaScript

You can use the following JavaScript code that scroll the browser to the top most page of the document.

window.scroll(0,0);

You can execute this code on onclick event of JavaScript hyper-link or on onclick event of any button or text as given below.

<script>
window.onload=function(){
var top=document.getElementById('top');
top.onclick=function(){window.scrollTo(0,0);}
</script>

You can call this function by placing id attribute within HTML file as given below.

<input type="button" value="Go To Top" id="top">

Preview:

How to Scroll Document Automatically Using JavaScript

You can scroll the document automatically using scrollBy() method which is similar to scroll() and scrollTo(), but its arguments are relative and are added to the current scrollbar offsets.

For example, you can use the following code to scroll 10 pixels down every 200ms.

javascript:void setInterval(function(){scrollBy(0,10)}, 200);

How to Scroll Document to View Certain Element Using JavaScript

Instead of scrolling to a numeric location in document, you can just scroll that a certain element in the document is visible. It can be done easily scrollIntoView() method on the desired HTML element and this method insures that the element on which it is invoked is visible in the viewport.

By default, the scrollIntoView() method tries to put the top edge of the element at or near the top of the viewport. The browser will also scroll the viewport horizontally as needed to make the element visible.

Related Search Terms

تصنيف: JavaScript Programming Guide

الأربعاء، 25 فبراير 2015

How to Create Table of Contents Using JavaScript

بواسطة: Unknown فبراير 25, 2015 أضف تعليق

You can create dynamic table of contents for any HTML document using JavaScript which can show the list of headings from h1 to h6 with links to the headings and make easier to navigate through the document.

In this post I am going to describe about the steps to Create Table of Contents Using JavaScript and about the JavaScript codes required to create dynamic table of contents.

To create this set of JavaScript codes for creating table of contents, at first you have to know the different JavaScript concepts like selecting elements, document traversal, setting element attributes, setting innerHTML property, creating nodes and inserting then into the document.

Steps to Create Table of Contents Using JavaScript

At first create window.onload function that runs automatically when the document finishes loading as given below.

window.onload=function(){

function getSelectedText(){
if (window.getSelection)
return window.getSelection().toString()+"
"+document.URL;
else if (document.selection)
 return document.selection.createRange().text+"
"+document.URL;
}
var toc=document.getElementById("TOC");
if(!toc) {
 toc=document.createElement("div");
 toc.id="TOC";
 document.body.insertBefore(toc, document.body.firstChild);
}

When the above function runs, it first looks for a document element with an id of "TOC". If there is no such element it creates on at the start of the document.

Add the following codes to the function to find all <h1> through <h6> tags and sets them as headings.

var headings;
if (document.querySelectorAll) 
headings=document.querySelectorAll("h1, h2, h3, h4, h5, h6");
else
headings=findHeadings(document.body, []);

Then recursively traverse the document body looking for headings using function: findHeadings(root, sects){ }

Initialize an array: var sectionNumber=[0,0,0,0,0,0]; that keeps track of section numbers and add section numbers to each section numbers to each section heading and wrap the headings in named anchors so that the TOC can link to them.

Write CSS code to style created table of contents. Where all entries have a class "TOCEntry" and the section headings from <h1> to <h6> have class name "TOCLevel1" to "TOCLevel6" and the section number inserted into headings have class "TOCSectNum".

Full CSS Code To Style Table of Contents

Here is a full CSS code within <style> </style> tag to style table of contents.

<style>
#TOC {border:solid black 1px; margin:10px; padding:10px;}
.TOCEntry{font-family:sans-serief;}
.TOCEntry a{text-decoration:none;}
.TOCLevel1{font-size:17pt; font-weight:bold;}
.TOCLevel2{font-size:16pt; font-weight:bold;}
.TOCLevel3{font-size:15pt; font-weight:bold;}
.TOCLevel4{font-size:14pt; margin-left:.25in;}
.TOCSectNum{display:none;}
</style>

Full JavaScript Code To Create Table of Contents

Here is a full JavaScript Code To Create Table of Contents within <script> </script> tag.

<script>
window.onload=function(){

function getSelectedText(){
if (window.getSelection)
return window.getSelection().toString()+"<br/>"+document.URL;
else if (document.selection)
 return document.selection.createRange().text+"<br/>"+document.URL;
}

var toc=document.getElementById("TOC");
if(!toc) {
 toc=document.createElement("div");
 toc.id="TOC";
 document.body.insertBefore(toc, document.body.firstChild);
}
var headings;
if (document.querySelectorAll) 
headings=document.querySelectorAll("h1, h2, h3, h4, h5, h6");
else
headings=findHeadings(document.body, []);

function findHeadings(root, sects){
 for(var c=root.firstChild; c!=null; c=c.nextSibling){
if (c.nodeType!==1) continue;
if (c.tagName.length==2 && c.tagName.charAt(0)=="H")
sects.push(c);
else
findHeadings(c, sects);
}
return sects;
}

var sectionNumbers=[0,0,0,0,0,0];

for(var h=0; h<headings.length; h++) {
 var heading=headings[h];

if(heading.parentNode==toc) continue;

var level=parseInt(heading.tagName.charAt(1));
if (isNaN(level)||level<1||level>6) continue;

sectionNumbers[level-1]++;
for(var i=level; i<6; i++) sectionNumbers[i]=0;

var sectionNumber=sectionNumbers.slice(0, level).join(".");

var span=document.createElement("span");
span.className="TOCSectNum";
span.innerHTML=sectionNumber;
heading.insertBefore(span, heading.firstChild);
heading.id="TOC"+sectionNumber;
var anchor=document.createElement("a");
heading.parentNode.insertBefore(anchor, heading);
anchor.appendChild(heading);

var link=document.createElement("a");
link.href="#TOC"+sectionNumber; 
link.innerHTML=heading.innerHTML;

var entry=document.createElement("div");
entry.className="TOCEntry TOCLevel" + level;
entry.appendChild(link);

toc.appendChild(entry);
}
};

</script>

You can see the preview of Table of contents generated by JavaScript code above. If you have any problem or difficulties while implementing the above JavaScript code, you are welcomed to mention on the comment session at the bottom this post.

Related Search Terms

تصنيف: JavaScript Programming Guide

الاثنين، 23 فبراير 2015

How to Select Document Elements Using JavaScript?

بواسطة: Unknown فبراير 23, 2015 أضف تعليق

You have to select the document elements for manipulation of elements of document to complete any task for the document design or action of the document using JavaScript codes.

There are number of ways to select elements to query a document for an element or elements in order to manipulate elements of the document, to obtain or select the element objects that refer to those document elements.

The different ways to select elements to query a document are explained below.

Selecting Elements By ID Attribute

Any of the HTML element can have the unique id attribute within the document. You can select an element based on this unique id with getElementById() method of the document object.

To select any element with id 'elt' you can use the following code.

var elt=document.getElementById('elt');

Selecting Elements By Name Attribute

Name attribute assigns the name of the element and it does not have to be unique. You can select the elements by name using getElementsByName() method.

To select any element with name 'address' you can use the following code.

var addresses=document.getElementsByName("address");

If there is a only one element with a given name, you use the name directly as the document property to assign the value of the element as given below.

To get the element for the from <form name="addresses">, you can use the following code.

var addresses=document.addresses;

Selecting Elements By TagName

You can select any HTML or XML elements by tagName using the getElementsByTagName() method of the document object. To select all <p> elements, you can use the following code.

var para=document.getElementsByTagName("p");

You can select any element with given tagName with specifying the position number according to the order of the document. You can select first <p> element of the document using the following.

var firstpara=document.getElementsByTagName("p")[0];

Also to find all <span> elements inside the first <p> element of document, you can write.

var firstpara=document.getElementsByTagName("p")[0];
var firstparaspans=firstpara.getElementsByTagName("span");

Selecting Elements By CSS Class

It is the another way to select elements from the document. You can select one or more elements with the given class name by using getElementsByClassName() method.

To select elements with ClassName 'color' you can use the following code.

var colors=document.getElementByClassName("color");

If you have to select elements having more than one class name, can do as below.

To select any element with ClassName 'color' and 'design' you can use the following code.

var colors=document.getElementByClassName("color design");

Selecting Elements By CSS Selectors

You can also select document elements with specifying CSS selectors which are used on CSS style-sheet. You can select one or more elements with the given CSS selectors by using querySelectorAll method.

To select an element with id 'nav' you can use the following code.

var nav=document.querySelectorAll("#nav");

To select a paragraph written in english you can use the following code.

var eng=document.querySelectorAll("p[lang="en"]");

Here are other examples of CSS selectors to select elements from the document.

#log span     // selects any <span> descendant of the element with id="log"

#log>span     // Selects <span> child of the element with id="log"

*[name="x"]     // Selects any element with a name="x" attribute.

You can also use document.all[] method, which is a collection that represented all the elements in the document as the following although this method is replaced by standard methods like getElementById() and getElementsByTagName().

document.all[0]         // Selects the first element in the document
document.all["navbar"]         // Selects all elements with id or name="navbar"
document.all.tags("div")     // Selects all <div> elements in the document
document.all.tags("p")[0]     // The first <p> in the document

Related Search Terms

تصنيف: JavaScript Programming Guide

الأحد، 22 فبراير 2015

How to go Back Browsing History Using JavaScript

بواسطة: Unknown فبراير 22, 2015 أضف تعليق

The history property of the window object refers to the history object for the window. Using history in JavaScript you can go back to the previous browsing history.

The history object models the browsing history of a window as a list of document and document states and the length property of the history object specifies the number of elements in the browsing history list.

The history object has back() and forward() methods that behave like the browser's back and forward buttons do, they make the browser go backward or forward one step in its browsing history.

history.back(); // Go back to the browsing history
history.forward(); //Go forward to the browsing history

Creating Buttons for History Back and Forward

You can create buttons to navigate browsing history back and forward using the following code.

<input type=button name="back" value="Go Back" onclick="history.back();">

<input type=button name="forward" 
value="Go Forward"onclick="history.forward();">

Preview:

A third method, go(), takes an integer argument and can skip any number of pages forward or backward in the history list.

history.go(-2) //go back 2, like clicking the back button twice

Creating Buttons for History Back and Forward for Specific Page

You can create buttons to navigate browsing history two step back using the following code.

<input type=button name="backward2"
value="Go Back 2" onclick="history.go(-2);">

Preview:

Using history.go() method, if you want to go forward, can use positive arguments and if you want to go back, can use negative argument and the number used on the argument represents how many steps to go back or forward.

For example, if you want to go two step forward to the browsing history, can use history.go(2); and if you want to go three step backward to the browsing history, can use history.go(-3);

If a window contains child windows such as <iframe> elements, the browsing histories of the child windows are chronologically interleaved with the history of the main window. This means that calling history.back(); on the main window may cause one of the child windows to navigate back to a previously displayed document but leave the main window in its current state.

If a frame is contained within another frame that is contained within a top-level window, that frame can refer to the top-level window as parent. For parent window to navigate back to a previously displayed document you can use parent property as below.

parent.history.back();

I have described here some methods of navigating browsing history back and forward using JavaScript . If you know other more methods of navigating browsing history back and forward using JavaScript, you are welcomed to mention on the comment session at the bottom this post.

Related Search Terms

تصنيف: JavaScript Programming Guide

الجمعة، 20 فبراير 2015

How to Click Button Using JavaScript?

بواسطة: Unknown فبراير 20, 2015 أضف تعليق

Buttons on a web-page allows users to submit data or to do any action on it and generally the actions are performed by clicking on it. Different types of buttons are used on web-page and they may be inside a form or outside a form for certain action to be performed. Buttons used within a form may be Submit Button, Reset Button, Browse Button etc.

You can set the actions performed by submit and reset buttons on a form with in a <form> tag as below.

<form action="submitpage.html" onsubmit="return validate(this)"
onreset="return conform()" method="post">
<!--Other Form Elements-->
<input type="submit" value="Submit">
<input type="reset" value="Reset">
</form>

In the above code, when submit button was clicked it goes to the page "submitpage.html" after validating the form by the function validate() and when reset button was clicked it clears all the form data after displaying conformation box by the function conform().

It is easier to do any task on clicking event of a button by executing certain JavaScript functions when the button was clicked. There are different ways to execute JavaScript codes on button click. In this post I am going to describe about those different methods of clicking buttons using JavaScript.

Different Ways to Click Button Using JavaScript

You can click button using JavaScript with the different methods given below.

With directly specifying JavaScript Built-in function on onClick event of Button

<input type="button" value="Display Time" 
onClick="alert(new Date().toLocaleTimeString());">

Preview:

With creating a JavaScript function and specifying it on onClick event of Button as given on the previous post: "How to create Timer Using JavaScript?"

<script>

var c=0

var t

function timedCount()

{

document.getElementById('txt').value=c

c=c+1

t=setTimeout("timedCount()", 1000)

}

</script>

<input type="button" value="Start Count" onClick="timedCount()">

<input type="button" value="0" id="txt">

Preview:

With creating a JavaScript function along with specifying onClick event of Button

<script>

window.onload=function(){

var btn=document.getElementById('btn');

btn.onclick=function(){alert("You Have Clicked Button");}

};

</script>

<input type=button id='btn' value='click me'>

Preview:

With specifying single function for multiple buttons having same class name by using for loop on onClick event of button

<script>

window.onload=function(){

var btns=document.getElementsByClassName('bt');

for(var i=0; i<btns.length; i++){

var bt=btns[i];

bt.onclick=function(){alert("You Have Clicked Button");}

}

};

</script>

<input type=button class='bt' value='Button 1'>

<input type=button class='bt' value='Button 2'>

<input type=button class='bt' value='Button 3'>

Preview:

I have described here some methods of clicking buttons using JavaScript . If you know other more methods of clicking buttons using JavaScript, you are welcomed to mention on the comment session at the bottom this post.

Related Search Terms

تصنيف: JavaScript Programming Guide

الأربعاء، 18 فبراير 2015

How to Create JavaScript Bookmarklet?

بواسطة: Unknown فبراير 18, 2015 أضف تعليق

Bookmarklet is a small JavaScript code which is saved on a browser's bookmark while bookmarking JavaScript: URL. It is a mini program that can be easily launched from the browser's menus or toolbar.

The code in a bookmarklet runs as if it ware a script on a page and can query and set document content presentation, and behavior. As long as a bookmarklet does not return a value, it can operate on whatever document is currently displayed without replacing that document with new content.

How to Create JavaScript Bookmarklet?

To create bookmarklet on your browser, either you can create HTML file containing JavaScript: URL and can bookmark it right clicking on the link and selecting something like bookmark link or dragging the link to your bookmarks toolbar or you can directly add new bookmark with add new bookmark option on the browser.

Here is a simple HTML code to create JavaScript URL link with a simple JavaScript code to display current time which I have previously mentioned on my previous post "How to Write JavaScript Function as URL in Hyperlink".

<a href="javascript:alert(new Date().toLocaleTimeString());"> 
check the document without writing the docment</a>

To check bookmarklet for your browser, save on bookmark the link given below which is generated from the code given above.

Check the document without writing the document

Another example of JavaScript:URL link in an <a> tag is given below, which opens a simple JavaScript expression evaluator that allows you to evaluate expressions and execute statements in the context of the page.

<a href='javascript:
var e="", r=""; /*expression evaluate the result*/
do{
/*display expression and result and ask for a new expression*/
e=prompt("Expression:"+e+"\n"+r+"\n", e);
try{r="Result:"+eval(e);} /*try to evaluate the expression*/
catch(ex){r=ex;} 
} while(e); /*continue until no expression entered or cancel clicked*/
void 0;'> 
Javascript Evaluator </a>

Even the above JavaScript:URL is written in multiple lines, the HTML parser treats it a single line, and in a single line code comments using // will not work so comments are created using /* and */. The preview of the code above is given below.

JavaScript Evaluator

You can save this link on your browsers bookmarks and check it by lunching the bookmark.

Related Search Terms

تصنيف: JavaScript Programming Guide

الاثنين، 16 فبراير 2015

How to Write JavaScript Function as URL in Hyperlink?

بواسطة: Unknown فبراير 16, 2015 أضف تعليق

You can write JavaScript function as like URL in hyperlink on href attribute of <a>....</a> tag. Writing JavaScript codes in a URL is another way that JavaScript code can be included in the client side using javascript: protocol specifier. This special protocol type specifies that the body of the URL is an arbitrary string of JavaScript code to be run by the JavaScript interpreter.

The "resource" identified by a javascript: URL is the return value of the executed code, converted to a string. If the code has an undefined return value, the resource has no content.

You can use a javascript: URL anywhere you'd use a regular URL: on the href attribute of <a> tag, on the action attribute of a <form>, on the click event of a button, on the method like window.open() etc.

The syntax for writing JavaScript function within href attribute of <a> tag is given below.

<a href="javascript:myfunction();">JavaScript Link</a>

And the syntax for writing JavaScript function within the action attribute of a <form> tag is given below.

<form action="myfunction();" onsubmit="return validate(this);" method="post"> .......</form>

An example for getting new date using javascript function as a hyperlink is given below.

<a href="javascript:new Date().toLocaleTimeString();"> What time is it?</a>

While using such functions on a hyperlink, some browsers like Firefox and IE execute the code in the URL and use the returned string as the content of a new document to display.

Just as when following a link to an http:URL, the browser erases the current document and displays the new one. The value returned by the code above does not contain any HTML tags.

Other browsers like chrome and safari do not allow URLs like the one above to overwrite the containing document, they just ignore the return value of the code. But they support the JavaScript code to display the returned content on alert box as below.

<a href="javascript:alert(new Date().toLocaleTimeString());"> check the document without writing the docment</a>

In the above cases, the javascript:URL serves the same purpose as an on-click event handler. The link The link above would be better expressed as an on-click handler on a <button> element. The <a> element generally reserved for hyperlinks that load new documents.

If you want to open a new document using a javascript: URL which does not overwrite the document, you can use void operator with window.open method as given below.

<a href="javascript:void window.open('http://www.siteforinfotech.com/p/javascript-programming-tutorials.html');">Open link on new window</a>

If you want to open a new document using a javascript: URL which overwrite the current document, you can use location.replace method as given below.

<a href="javascript:location.replace('http://www.siteforinfotech.com/p/javascript-programming-tutorials.html');">Open window using location.replace</a>

Like HTML event handler attributes, JavaScript URLs are a holdover from the early days of the web and generally avoided in modern HTML. JavaScript: URLs are very useful if you need to test a small snippet of JavaScript code, you can type a javascript:URL directly into the location bar of your browser. And another most powerful use of Javascript:URLs is in browser bookmarks.

Related Search Terms

تصنيف: JavaScript Programming Guide

الجمعة، 13 فبراير 2015

How to create a Simple calculator Using HTML and JavaScript

بواسطة: Unknown فبراير 13, 2015 أضف تعليق

Here are the steps to create a simple calculator using HTML and JavaScript which can evaluate simple arithmetic on integer numbers. Two types of inputs text and button are used here on a table within a form element and OnClick event was used to insert button values on the screen or to evaluate the numbers.

Steps to create a Simple calculator Using HTML and JavaScript

1. At first Insert a <form> element within <body> tag.
2. Create a table using <table> .....</table> tag.
3. Insert two types of Input text and button within table data of table row using <tr><td>....</td></tr> tag.
4. Assign OnClick event for all the buttons having numbers and arithmetic operators.
5. Give blank value for Clear(C) button.
6. Use eval() function to evaluate the numbers on OnClick event of equal to sign button.

Full HTML code for a Simple HTML calculator

<html>
<head></head>
<body>
<h3>Simple Calculator</h3>
<br/>
<form Name="calc">
<table border=2>
<tr>
<td colspan=4><input type=text Name="display"></td>
</tr>
<tr>
<td><input type=button value="0" OnClick="calc.display.value+='0'"></td>
<td><input type=button value="1" OnClick="calc.display.value+='1'"></td>
<td><input type=button value="2" OnClick="calc.display.value+='2'"></td>
<td><input type=button value="+" OnClick="calc.display.value+='+'"></td>
</tr>
<tr>
<td><input type=button value="3" OnClick="calc.display.value+='3'"></td>
<td><input type=button value="4" OnClick="calc.display.value+='4'"></td>
<td><input type=button value="5" OnClick="calc.display.value+='5'"></td>
<td><input type=button value="-" OnClick="calc.display.value+='-'"></td>
</tr>
<tr>
<td><input type=button value="6" OnClick="calc.display.value+='6'"></td>
<td><input type=button value="7" OnClick="calc.display.value+='7'"></td>
<td><input type=button value="8" OnClick="calc.display.value+='8'"></td>
<td><input type=button value="x" OnClick="calc.display.value+='*'"></td>
</tr>
<tr>
<td><input type=button value="9" OnClick="calc.display.value+='9'"></td>
<td><input type=button value="C" OnClick="calc.display.value=''"></td>
<td><input type=button value="=" OnClick="calc.display.value=eval(calc.display.value)"></td>
<td><input type=button value="/" OnClick="calc.display.value+='/'"></td>
</tr>
</table>
</form>
</body>
</html>

Preview of Simple HTML calculator

Related Search Terms

تصنيف: JavaScript Programming Guide

الخميس، 12 فبراير 2015

How to use Round, Random, Min and Max in JavaSript

بواسطة: Unknown فبراير 12, 2015 أضف تعليق

Round, Random, Min and Max are the methods used in math object in JavaSript. Math object allows you to perform common mathematical tasks. The math object includes several mathematical values and functions. Yo do not need to define the math object before using it. In this post I am describing How to use Round, Random, Min and Max in JavaSript.

How to use Round() in JavaScript

Using round() method in math object, you can round the given numbers as given below.

<script>
document.write(Math.round(0.60) +"<br/>");
document.write(Math.round(0.40) +"<br/>");
document.write(Math.round(0.49) +"<br/>");
document.write(Math.round(-3.69) +"<br/>");
document.write(Math.round(-6.10) +"<br/>");
</script>

Preview:

How to use Random() in JavaScript

You can use the random() method in math object,you can return a random number between 0 and 1 as given below.

<script>
document.write(Math.random());
</script>

Preview:

How to use Max() in JavaScript

Using max() method in math object, you can return the number with the highest value of two specified numbers as the following.

<script>
document.write(Math.max(9,3) +"<br/>");
document.write(Math.max(-5,7) +"<br/>");
document.write(Math.max(10,21) +"<br/>");
document.write(Math.max(-5,-9) +"<br/>");
document.write(Math.max(6.12,7.98) +"<br/>");
</script>

Preview:

How to use Min() in JavaScript

Using min() method in math object, you can return the number with the highest value of two specified numbers as the following.

<script>
document.write(Math.min(9,3) +"<br/>");
document.write(Math.min(-5,7) +"<br/>");
document.write(Math.min(10,21) +"<br/>");
document.write(Math.min(-5,-9) +"<br/>");
document.write(Math.min(6.12,7.98) +"<br/>");
</script>

Preview:

There are also other more methods on JavaScript math object to perform common mathematical tasks which are listed below along with their description. You can use them as the methods given above.

abs(x): Returns the absolute value of a number
ceil(x): Returns the value of a number rounded upwards to the nearest integer
exp(x): Returns the value or E^x.
floor(x): Returns the value of a number rounded downwards to the nearest integer.
log(x): Returns the natural logarithm (base E) of a number.
pow(x,y): Returns the value of x to the power of y.
sqrt(x): Returns the square root of a number.

Related Search Terms

تصنيف: JavaScript Programming Guide

الأحد، 8 فبراير 2015

How to Loop Through JavaScript Array?

بواسطة: Unknown فبراير 08, 2015 أضف تعليق

You can loop any Array by using different types of looping statements in JavaScript, which I have previously posted. In this post you can loop through JavaScript Array. At first let you know basic concepts of Array ie. defining array, adding values to the array and accessing array elements.

The Array object is used to store a set of values in a single variable name. You can define Array object with the new keyword.

The following line of code defines an Array object called myArray.

var myArray=new Array()

You can also define the array size by passing an integer argument as follows.

var myArray=new Array(5)

You can add the values to an array as the following.

var myArray=new Array()
myArray[0]="value1"
myArray[1]="value2"
myArray[2]="value3"

You can also give values to the arrays while defining it as below.

var myArray=new Array("value1", "value2", "value3")

While accessing Arrays, you can refer to a particular element in an array by referring to the name of the array and the index number. The index number starts at 0. The following line accesses the first value of the array myArray.

document.write(myArray[0])

Loop Through JavaScript Array

You can loop any Array by using any of the following looping statements in JavaScript.

Using For loop

You can loop any Array by using For Loop as below.

var myArray=new Array()
myArray[0]="value1"
myArray[1]="value2"
myArray[2]="value3"

for(i=0; i<myArray.length;i++)
{
document.write(myArray[i])
}

Example:

<html>
<head></head>
<body>
<script type="text/javascript">
var mycars=new Array()
mycars[0]="Saab"
mycars[1]="Volvo"
mycars[2]="BMW"

for(i=0; i<mycars.length;i++)
{
document.write(mycars[i]+"<br/>")
}
</script>

Preview:

Using For .... In Statement

You can loop any Array by using For .... In Statement as below.

var myArray=new Array()
myArray[0]="value1"
myArray[1]="value2"
myArray[2]="value3"

for(x in myArray)
{
document.write(myArray[x])
}

Example:

<html>
<head></head>
<body>
<script type="text/javascript">
var mycars=new Array()
mycars[0]="Saab"
mycars[1]="Volvo"
mycars[2]="BMW"

for(x in mycars)
{
document.write(mycars[x]+"<br/>")
}
</script>
</body>
</html>

Preview:

You can also loop any Array by using other looping statements like while and Do ... while loops as the same methods given above.

Related Search Terms

تصنيف: JavaScript Programming Guide

How to Loop using JavaScript?

بواسطة: Unknown فبراير 08, 2015 أضف تعليق

Loops in JavaScript are used to execute the same block of code a specified number of times or while a specified condition is true.

In JavaScript there are two different kinds of loops which are for loop, which loops through a block of code a specified number of times and while loop, which loops through a block of code while a specified condition is true.

JavaScript For Loop

The for loop is used when you know in advance how many times the script should run.

Syntax:

for(var=startvalue; var<=endvalue;var=var+increment)
{
code to be executed
}

Example:

<html>
<head>
</head>
<body>
<script type="text/javascript">
var i=0
for (i=0;i<=10;i++){

document.write("The number is" +i)
document.write("<br/>")}
</script>
</body>
</html>

The above example defines a loop that starts with i=0. The loop will continue to run as long as i is less than, or equal to 10. i will increase by 1 each time the loop runs.

Preview:

JavaScript While Loop

The while loop is ued when you want the loop to execute and continue executing while the specified condition is true.

Syntax:

while (var<=endvalue)
{
code to be executed
}

Example:

<html>
<head></head>
<body>
<script type="text/javascript">
var i=0
while(i<=10)
{
document.write("The number is "+i)
document.write("<br/>")
i=i+1
}
</script>
</body>
</html>

The example above defines a loop that starts with i=0. The loop will continue to run as long as i is less than, or equal to 10. i will increase by 1 each time the loop runs.

Preview:

JavaScript do .... while Loop:

The do .... while loop is a variant of the while loop. This loop will always execute a block of code Once, and then it will repeat the loop as long as the specified condition is true. The lop alway be executed at least once, even if the condition is false, because the code is executed before the condition is tested.

Syntax:

do
{
code to be executed
}
while (var<=endvalue)

Example:

<html>
<head></head>
<body>
<script type="text/Javascript">
var i=0
do
{
document.write("The number is "+i)
document.write("<br/>")
i=i+i
}
while (i<0)
</script>
</body>
</html>

Preview:

JavaScrpt Break and Continue Statements

There are two special statements that can be used inside loops: break and continue.

Break

The break command will break the loop and continue executing the code that follows after the loop.

Example:

Preview:

Continue

The continue command will break the current loop and continue with the next value.

Example:

Preview:

Related Search Terms

تصنيف: JavaScript Programming Guide

السبت، 7 فبراير 2015

How to Show Pop Up Boxes Using JavaScript?

بواسطة: Unknown فبراير 07, 2015 أضف تعليق

Using JavaScript you can create three kinds of pop-up boxes, Alert box, Confirm box and prompt box.

Alert Box

An alert box is used if you want to make sure information comes through to the user. When an alert box pops up, the user will have to click on "OK" to processed.

Syntax:

alert("Alert Text")

Example:

<html>

<head>

function display_alert()

{

alert("This is an alert box!")

}

</script>

</head>

<body>

</body>

</html>

Preview:

Conform box

A conform box is used if you want the user to verify or accept something. When a conform box pops up, the user will have to click either "OK" or "Cancel" to processed. If the user clicks "OK" the box returns true. If the user clicks "Cancel", the box returns false.

Syntax:

confirm{"Conform Text")

Example:

<html>

<head>

function display_conform(){

r=confirm("Press a button");
if (r===true)
{
alert("You pressed OK!");
}
else
alert("You pressed Cancel");
}

</script>

<body>

</body>

</html>

Preview:

Prompt Box

A prompt box is used if you want the user to input a value before entering a page. When a prompt box pops up, the user will have to click "OK" or "Cancel" to processed entering in input value.

If the use clicks "OK" the box returns the input value. If the user clicks "Cancel" the box returns null.

Syntax:

prompt{"sometext", "defaultvalue"}

Example:

<html>

<head>

function display_prompt(){
name=prompt("Please enter your name", "Your Name");
if ((name!=null) && name!=" ")
{
alert("Hello "+name+"! How are you today?");
}
}

</script>

</head>

</body>

</html>

Preview:

Related Search Terms

تصنيف: JavaScript Programming Guide

السبت، 28 فبراير 2015

How to Scroll Bottom of Document Using JavaScript

Preview:

How to Scroll Top of Document Using JavaScript

Preview:

How to Scroll Document Automatically Using JavaScript

How to Scroll Document to View Certain Element Using JavaScript

Related Search Terms

Related Posts:

الأربعاء، 25 فبراير 2015

Steps to Create Table of Contents Using JavaScript

Full CSS Code To Style Table of Contents

Full JavaScript Code To Create Table of Contents

Related Search Terms

Related Posts:

الاثنين، 23 فبراير 2015

Selecting Elements By ID Attribute

Selecting Elements By Name Attribute

Selecting Elements By TagName

Selecting Elements By CSS Class

Selecting Elements By CSS Selectors

Related Search Terms

Related Posts:

الأحد، 22 فبراير 2015

Creating Buttons for History Back and Forward

Creating Buttons for History Back and Forward for Specific Page

Related Search Terms

Related Posts:

الجمعة، 20 فبراير 2015

Different Ways to Click Button Using JavaScript

With directly specifying JavaScript Built-in function on onClick event of Button

With creating a JavaScript function and specifying it on onClick event of Button as given on the previous post: "How to create Timer Using JavaScript?"

With creating a JavaScript function along with specifying onClick event of Button

With specifying single function for multiple buttons having same class name by using for loop on onClick event of button

Related Search Terms