jQuery Tips and Tricks

jQuery Tips and Tricks

 Disabling Right Mouse Click


$(document).ready(function(){
$(document).bind("contextmenu",function(e){
return false;
});
});

Determine Browser

Suppose you were to determine the browser type of the browser currently in use. You can use the following piece of code to do this:

$(document).ready(function() {
// If the browser type if Mozilla Firefox
if ($.browser.mozilla && $.browser.version >= "1.8" ){
// some code
}
// If the browser type is Opera
if( $.browser.opera)
{
// some code
}
// If the web browser type is Safari
if( $.browser.safari )
{
// some code
}
// If the web browser type is Chrome
if( $.browser.chrome)
{
// some code
}
// If the web browser type is Internet Explorer
if ($.browser.msie && $.browser.version <= 6 ) { // some code } //If the web browser type is Internet Explorer 6 and above if ($.browser.msie && $.browser.version > 6)
{
// some code
}
});

Detect Current Mouse Coordinates

Now, suppose you need to detect the current mouse coordinates in the web browser in use. To do this, you can write the following piece of code:

$(document).ready(function() {
$().mousemove(function(e)
{
$('# MouseCoordinates ').html("X Axis Position = " + e.pageX + " and Y Axis Position = " + e.pageY);
});


});

Check if an Element Exists

To check whether an element exists, you can write the following code:

if ($("#someElement").length)
{
//The DOM element exists
}
else
{
//The DOM element doesn't exist
}

Check if an Element Is Visible

To check whether an element is visible, you can use the following piece of code:

if($(element).is(":visible") == "true")
{
//The DOM element is visible
}
else
{
//The DOM element is invisible
}

Set a Timer

The following piece of code can be used to set a timer using jQuery:

$(document).ready(function()
{
window.setTimeout(function()
{
// some code
}, 500);
});

JQuery’s Chaining Feature

Chaining is a great feature in jQuery that allows you to chain method calls. Here is an example:

$('sampleElement').removeClass('classToBeRemoved').addClass('classToBeAdded');

You can also use jQuery to store state information of DOM elements in your web page. It contains the data() method that you can use to store state information of the DOM elements in key/value pairs. Here is an example:

$('#someElement').data('currentState', 'off');

Lazy Loading

Lazy loading is a great feature in jQuery that ebales you to load only the content that is needed. To use this, you should incorporate the jquery.lazyload.js script file as shown below:





Next, you can use the lazyload() method as shown below:

$("imageObject").lazyload();

Preloading Images

Preloading images in a web page improves performance. This can particularly be useful while an animation is in progress- your web page need not wait for the image to be loaded. You can use jQuery to preload images with simple code. Here is an example:

jQuery.preloadImagesInWebPage = function() {
for(var ctr = 0; ctr").attr("src", arguments[ctr]);
}
}

To use the above method, you can use the following piece of code:

$.preloadImages("image1.gif", "image2.gif", "image3.gif");

To check whether an image has been loaded, you can use the following piece of code:

$('#imageObject').attr('src', 'image1.gif').load(function() {
alert('The image has been loaded…');
});

jQuery Cloning

jQuery supports cloning - you can use the clone() method to create a clone of any DOM element in your web page. Here is an example:

var cloneObject = $('#divObject').clone();

The $(document).ready function is called during page render, i.e., while the objects are still being downloaded in the web browser. To reduce CPU utilization while a page is being loaded, you can bind your jQuery functions in the $(window).load event. Note that this event is fired after all objects have been downloaded successfully. This would improve the application performance to a considerable extent as the page load time would be minimized. Other common ways to improve jQuery performance are by compressing the scripts and limiting DOM manipulation as much as possible.

Consider the following piece of code that appends a DOM element inside a loop:

for (var ctr=0; ctr<=rows.length; ctr++) { $('#tableObject').append(' '+rows[ctr]+'

');
}

The above code can be replaced by a more efficient piece of code to minimize DOM manipulation and hence improve application performance as shown below:

var str = '';
for (var x=0; x<=rows.length; x++) { str += ' '+rows[x]+'

';
}
$('#tableObject').append(str);