Run multiple AJAX requests in parallel

Some times it is best idea to issue multiple Ajax request in parallel. Without waiting one request to be completed we can issue multiple request using jquery when method

$.when($.get('files/1.json'), $.get('files/2.json')).then(function(r1, r2){
log(r1[0].message + " " + r2[0].message);
});

second argument to the $() function

What does second argument of $() function in jquery.

The second argument is context to limit the search

Suppose we have html like below

<ul id="firstList">
	<li>one</li>
	<li>two</li>
	<li>three</li>
</ul>
<ul id="secondList">
	<li>blue</li>
	<li>green</li>
</ul>

if we want to go through the li only under the firstList div we can use $() function’s second argument as below.

$('li','#firstList').each(function(){
console.log($(this).html());
});

 

Define an exists() function in Jquery

When we are in web development we have to check element is exist using Javascript. Below way we can check it.

console.log($('#elem').length == 1 ? "exists!" : "doesn't exist!");

But it can be cumbersome

So we can define a Jquery function as below

jQuery.fn.exists = function(){ return this.length > 0; }

console.log($('#elem').exists() ? "exists!" : "doesn't exist!");

Is it nice?…