Summary of jQuery skills_jquery

1. Introduction
1.1. Overview
With the rapid development and spread of WEB2.0 and ajax ideas on the Internet, some excellent Js frameworks have emerged one after another, among which the more famous ones are Prototype, YUI, jQuery, mootools, Bindows and domestic JSVM frameworks, etc., by applying these JS frameworks to our projects, programmers can be freed from designing and writing complex JS applications, and focus on functional requirements rather than implementation. details, thereby increasing the development speed of the project.
jQuery is another excellent Javascript framework after prototype. Created by John Resig in early 2006, it helps simplify JavaScript™ and Ajax programming. Some people use this metaphor to compare prototype and jQuery: prototype is like Java, and jQuery is like ruby. It is a simple, fast and flexible JavaScript framework that allows you to simply operate documents, handle events, and Implement special effects and add Ajax interaction to web pages.
It has the following characteristics:

Concise code, easy-to-understand semantics, fast learning, and rich documentation.
jQuery is a lightweight script, and its code is very small. The latest version of the JavaScript package is only about 20K.
jQuery supports CSS1-CSS3, as well as basic xPath.
jQuery is cross-browser, and the browsers it supports include IE 6.0, FF 1.5, Safari 2.0, Opera 9.0.
It is easy to extend other functions for jQuery.
It can completely separate JS code and HTML code, making it easier to code, maintain and modify.
Plug-ins are abundant. In addition to some special effects provided by jQuery itself, more functions can be implemented through plug-ins, such as form validation, tab navigation, drag-and-drop effects, table sorting, DataGrid, tree menu, image special effects, ajax upload, etc. .
The design of jQuery will change the way you write JavaScript code, reduce the complexity of learning to use JS to operate web pages, and improve the efficiency of web JS development. Whether you are a JS beginner or a senior expert, jQuery will be your first choice.
jQuery is suitable for designers, developers and those who are lucky, and is also suitable for commercial development. It can be said that jQuery is suitable for any JavaScript application and can be used in different web applications.
Official site: http://jquery.com/ Chinese site: http://jquery.org.cn/
1.2. Purpose
By studying this document, you can learn about jQuery Have a simple understanding of the differences between JQuery and other JS frameworks, and master the common syntax, usage skills and precautions of jQuery.
2. How to use
Introduce the js file of JQuery into the page that needs to use JQuery.
For example:
After being introduced, the syntax provided by jQuery can be used anywhere on the page.
3. Learning tutorials and reference materials
Please refer to the "jQuery Chinese API Manual" and http://jquery.org.cn/visual/cn/index.xml
Recommend two Good jquery tutorials: "jQuery Starting Tutorial" and "Using jQuery to Simplify Ajax Development"
4. Syntax summary and notes 1. References to page elements
Reference elements through jquery's $() include Methods such as id, class, element name, hierarchical relationship of elements, and dom or xpath conditions, and the returned object is a jquery object (collection object), and methods defined by dom cannot be directly called.
2. Conversion between jQuery objects and dom objects
Only jquery objects can use the methods defined by jquery. Note that there is a difference between dom objects and jquery objects. When calling methods, you should pay attention to whether you are operating on dom objects or jquery objects.
Ordinary dom objects can generally be converted into jquery objects through $().
For example: $(document.getElementById("msg")) is a jquery object, and you can use jquery methods.
Because the jquery object itself is a collection. Therefore, if the jquery object is to be converted into a dom object, one of the items must be retrieved, which can generally be retrieved through an index.
For example: $("#msg")[0], $("div").eq(1)[0], $("div").get()[1], $("td" )[5] These are dom objects, you can use methods in dom, but you can no longer use Jquery methods.
The following writing methods are correct:

Copy code The code is as follows:

$("#msg").html();
$("#msg")[0].innerHTML;
$("#msg").eq(0)[0].innerHTML;
$("#msg").get(0).innerHTML;

3. How to get an item of jQuery collection
for the obtained element collection , to obtain one of the items (specified by index), you can use the eq or get(n) method or the index number. Note that eq returns a jquery object, while get(n) and index return a dom element object. For jquery objects, you can only use jquery methods, and for dom objects, you can only use dom methods. For example, you want to get the content of the third

element. There are two methods:

Copy the code The code is as follows:

$("div").eq(2).html(); //Call the method of jquery object
$("div").get(2).innerHTML; //Call dom The method attributes of

4. The same function implements set and get
This is true for many methods in Jquery, mainly including the following:

Copy code The code is as follows:

$("#msg").html(); //Return The html content of the element node with id msg.
$("#msg").html("new content");
//Write "new content" as an html string In the content of the element node with the id of msg, the page displays bold new content
$("#msg").text(); //Return the text content of the element node with the id of msg.
$("#msg").text("new content");
//Write "new content" as a normal text string Enter the element node content with id msg, and the page displays new content
$("#msg").height(); //Return the height of the element with id msg
$("#msg").height("300"); //Set the height of the element with id msg to 300
$("#msg").width(); //Return the element with id msg The width of the element
$("#msg").width("300"); //Set the width of the element with id msg to 300
$("input").val("); / /Return the value of the form input box
$("input").val("test"); //Set the value of the form input box to test
$("#msg").click( ); //Trigger the click event of the element with id msg
$("#msg").click(fn); //Add a function for the click event of the element with id msg

Similarly, blur, focus, select, and submit events can have these two calling methods
5. Collection processing function
For the collection content returned by jquery, we do not need to loop through it ourselves and process each Each object is processed separately. jquery has provided us with a very convenient method for processing collections.
includes two forms:

Copy code<.> The code is as follows:

$("p").each(function(i){this.style.color=['#f00','#0f0','# 00f']})
//Set different font colors for the p elements with indexes 0, 1, and 2 respectively.
$("tr").each(function(i){this.style. .backgroundColor=['#ccc','#fff'][i%2]})
//Achieve the interlaced color changing effect of the table
$("p").click(function(){alert ($(this).html())})
//Added click event for each p element. Clicking on a p element will pop up its content

6 , extend the functions we need

Copy code The code is as follows:

$.extend ({
min: function(a, b){return a < b?a:b; },
max: function(a, b){return a > b?a:b; }
}); //Extended min and max methods for jquery

Use the extended method (called through "$.method name"):
alert("a=10 ,b=20,max=" $.max(10,20) ",min=" $.min(10,20));

7. Support the continuous writing of methods
so-called Continuous writing means that you can continuously call various methods on a jquery object. For example:
$("p").click(function(){alert($(this).html())})
.mouseover(function(){alert('mouse over event ')})
.each(function(i){this.style.color=['#f00','#0f0','#00f']});

8. Manipulate elements The style of mainly includes the following methods:

Copy code The code is as follows:

$("#msg").css("background"); //Return the background color of the element
$("#msg").css("background","#ccc") //Set Set the background of the element to gray
$("#msg").height(300); $("#msg").width("200"); //Set the width and height
$("#msg ").css({ color: "red", background: "blue" });//Set styles in the form of name-value pairs
$("#msg").addClass("select"); / /Add a class named select to the element
$("#msg").removeClass("select"); //Remove the class named select for the element
$("#msg").toggleClass(" select"); //If it exists (does not exist), delete (add) the class named select


9. Complete event processing function
Jquery has provided us with various event processing methods. We do not need to write events directly on html elements, but can directly process objects obtained through jquery. Add event.
For example:
$("#msg").click(function(){alert("good")}) //Added a click event to the element
$("p").click (function(i){this.style.color=['#f00','#0f0','#00f']}) //Set different processing for three different p element click events
Several custom events in jQuery:
(1)hover(fn1,fn2): A method that imitates hover events (the mouse moves over an object and out of the object). When the mouse moves over a matching element, the first specified function will be triggered. When the mouse moves out of this element, the specified second function will be triggered.
//When the mouse is placed on a row of the table, set the class to over and set it to out when leaving.
$("tr").hover(function(){
$(this).addClass("over");
},
function(){
$(this) .addClass("out");
});
(2) ready(fn): Bind a function to be executed when the DOM is loaded and ready for query and manipulation.
$(document).ready(function(){alert("Load Success")})
//When the page is loaded, it prompts "Load Success". Different from the onload event, onload requires that the page content has been loaded (picture etc.), and ready is triggered as soon as the page html code is downloaded. Equivalent to $(fn)
(3) toggle(evenFn,oddFn): Switch the function to be called every time it is clicked. If a matching element is clicked, the first function specified is triggered, and when the same element is clicked again, the second function specified is triggered. Each subsequent click repeats the call to these two functions in turn.
//Rotate adding and deleting the class named selected every time you click.
$("p").toggle(function(){
$(this).addClass("selected");
},function(){
$(this).removeClass( "selected");
});
(4) trigger(eventtype): Trigger a certain type of event on each matching element.
For example:
$("p").trigger("click"); //Trigger the click event of all p elements
(5) bind(eventtype,fn), unbind(eventtype): event Binding and unbinding
removes (adds) the bound event from each matching element.
For example:
$("p").bind("click", function(){alert($(this).text());});
//For each p element Add click event
$("p").unbind(); //Delete all events on all p elements
$("p").unbind("click") //Delete all p elements Click event on
10. Several practical special effects functions
Among them, the toggle() and slidetoggle() methods provide state switching function.
For example, the toggle() method includes hide() and show() methods.
The slideToggle() method includes the slideDown() and slideUp methods.
11. Several useful jQuery methods
$.browser. Browser type: Detect browser type. Valid parameters: safari, opera, msie, mozilla. For example, if you check whether it is IE: $.browser.isie, if it is an IE browser, it will return true.
$.each(obj, fn): General iteration function. Can be used to iterate over objects and arrays approximately (instead of looping).
For example,
$.each( [0,1,2], function(i, n){ alert( "Item #" i ": " n ); });
is equivalent to:
var tempArr=[0,1,2];
for(var i=0;ialert("Item #" i ": " tempArr);
}
can also process json data, such as
$.each( { name: "John", lang: "JS" }, function(i, n){ alert( "Name: " i ", Value : " n ); });
The result is:
Name:name, Value:John
Name:lang, Value:JS
$.extend(target,prop1,propN): Use a or multiple other objects to extend an object, returning the extended object. This is the inheritance method implemented by jquery.
For example:
$.extend(settings, options);
//Merge settings and options, and return the merged result to settings, which is equivalent to options inheriting setting and saving the inherited result in setting.
var settings = $.extend({}, defaults, options);
//Merge defaults and options, and return the merged result to the setting without overwriting the default content.
Can have multiple parameters (combine multiple parameters and return)
$.map(array, fn): array mapping. Saves the items in an array (after processing the transformation) into a new array and returns the resulting new array.
For example:
var tempArr=$.map( [0,1,2], function(i){ return i 4; });
The content of tempArr is: [4,5,6]
var tempArr=$.map( [0,1,2], function(i){ return i > 0 ? i 1 : null; });
The content of tempArr is: [2,3]
$.merge(arr1,arr2): Merge two arrays and delete duplicate items.
For example:
$.merge( [0,1,2], [2,3,4] ) //Return [0,1,2,3,4]
$.trim(str ): Remove whitespace characters at both ends of the string.
For example:
$.trim(" hello, how are you? "); //Return "hello, how are you? "

12. Solve custom methods or other Conflict between class library and jQuery
Many times we define the $(id) method ourselves to get an element, or some other js libraries such as prototype also define the $method. If we put these contents at the same time Together, it will cause a variable method definition conflict, and Jquery specifically provides a method to solve this problem.
Use the jQuery.noConflict(); method in jquery to transfer control of the variable $ to the first library that implements it or the previously customized $ method. When using Jquery later, just replace all $ with jQuery. For example, the original reference object method $("#msg") is changed to jQuery("#msg").
For example:

Copy code The code is as follows:

jQuery.noConflict();
// Start using jQuery
jQuery("div p").hide();
// Use other libraries' $()
$("content").style.display = 'none ';

Statement：

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn