Question: What is jQuery?
jQuery is a fast, small and feature-rich JavaScript library.
jQuery makes things like HTML document
traversal and
manipulation,
animation,
event handling and Ajax much simpler with an easy-to-use API.
It works across a multitude of browsers.
Question: What is Ajax?
Ajax( Short form of
Asynchronous
JavaScript and
XML) is a Web development techniques used on the client-side to create Synchronous OR asynchronous Web applications. It is used to get the data from server without refresh the page.
Question: What is Iframe?
Iframe is an HTML document embedded inside another HTML document on a website. We can embed one OR many iframe in one website.
Question: What is element in HTML?
An HTML element is an individual component of an HTML document or web page.
For example, p,div,span etc know as element.
when these surrounded by angle brackets know as HTML Tags.
Question: What is event in jQuery?
Doing any thing, known as event.
For Example, Click event, mouseover event, blur event, double click event etc.
Question: What is jQuery event?
A jQuery object is array-like which means that it contains zero or more indexes.
Question: How to parse a JSON String?
var obj = jQuery.parseJSON( '{ "name": "John" }' );
console.log( obj.name);
Question: How to communicate between iframe and the parent site?
With
same domain and
same port/protocol
you can use
window.opener to change in parent window from child window.
you can use
document.getElemetById('#iframeId') to change in child window from parent window.
With
different domain OR
different port/protocol
You have to use
cross-document messaging.
Question: How can I select an element by name or class or id with jQuery?
Select by name
console.log($('div[name=divname]'));
Select by class name
console.log($('div.className'));
Select by classId
console.log($('div#classId'));
Question: How to show the preview an image before it is uploaded to server?
To show the preview you need to use "FileReader" javascript function.
See Demo:http://jsfiddle.net/LvsYc/
Question: How to get html tags from string?
var re = /(<([^>]+)>)/ig;
var str = '
Hello!
';
var m;
while ((m = re.exec(str)) !== null) {
if (m.index === re.lastIndex) {
re.lastIndex++;
}
}
console.log(re);
Question: What is use $.each? Give examples?
It is similar to
foreach in jQuery.
you can use $.each for normal array OR list of elements.
For Example:
$('a.myclass').each(function(index, value){
console.log($(this).attr('href'));
});
var numberArray = [0,1,2,3,4,5];
jQuery.each(numberArray , function(index, value){
console.log(index + ':' + value);
});
Question: What's the difference between jquery.js and jquery.min.js?
Both are
same.
only
difference jquery.min.js is minified file which have no space, tab.
Question: How to add Email Validation in jQuery?
function IsValidEmail(email) {
var regex = /^([a-zA-Z0-9_.+-])+\@(([a-zA-Z0-9-])+\.)+([a-zA-Z0-9]{2,4})+$/;
return regex.test(email);
}
console.log(IsValidEmail('myvalidemail@domain.com'));
console.log(IsValidEmail('myInvalidemail@'));
console.log(IsValidEmail('myInvalidemail#domain.com'));
Question: How to get nth jQuery element?
use
eq function.
console.log($("div.myclass:eq(2)"));
Question: How to remove a row from table?
$('tr#myTableRowId').remove();
OR
$('tr.myTableRowClass').remove();
Question:How to bind shortcut-keys with jQuery?
To bind Ctrl+f to a
functionName.
$(document).bind('keydown', 'ctrl+f', functionName);
You can check also:
http://github.com/jeresig/jquery.hotkeys
Question: How to convert array to JSON?
You can use
stringify.
var yourArray = Array('1','2','3','4');
var myJsonString = JSON.stringify(yourArray);
Question: How to check if a div exists with jquery?
if($("div#idName" + name).length > 0) {
/** It is exist **/
}
Question: How to call a function after 3 seconds?
setTimeout(
function(){
/** Do here **/
/** Do here **/
}, 3000);
}
Question: How to prevent caching in Ajax?
After loading of jQuery, add the
below code at the top of all ajax call.
$.ajaxSetup({ cache: false });
