Detailed compilation of jQuery common development techniques_jquery

1. References about page elements
Referencing elements through jquery's $() includes methods such as id, class, element name, hierarchical relationship of elements, dom or xpath conditions, etc., and the returned object is jquery objects (collection objects) cannot directly call methods defined by dom.

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 the following two methods:
$(“div”).eq(2).html(); //Call the jquery object method
$(“div”).get(2).innerHTML; / /Call dom method attributes
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 element node with id msg html content.
$("#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 two calling methods

5. Collection processing function
For the collection content returned by jquery, we do not need to loop through it ourselves and Each object is processed separately. jQuery has provided us with a very convenient method to process collections.
includes two forms:

Copy code The code is as follows:

$("p").each(function(i){this.style.color=['#f00','#0f0', '#00f'][ i ]})
//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 www.222gs.com
$(“p ”).click(function(){alert($(this).html())})
//A click event is added for each p element. Clicking on a p element will pop up its content

6. Expand the functions we need

Copy the 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 method Continuous writing
The so-called continuous writing means that you can continuously call various methods on a jquery object.
For example:

Copy code The code is as follows:

$("p"). click(function(){alert($(this).html())})
.mouseover(function(){alert('mouse over event')})
.each(function(i){ this.style.color=['#f00','#0f0','#00f'][ i ]});

8. Style of operating elements
Mainly include 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 the background of the element to gray
$(“#msg”).height(300); $(“#msg”).width(“200″); //Set width and height
$(“#msg”).css({ color: “red”, background: “blue” });//Set the style in the form of name-value pairs www.52mvc.com
$(“#msg”).addClass(“select”); // Add a class named select to the element
$(“#msg”).removeClass(“select”); //Remove the class named select
$(“#msg”).toggleClass(“select ”); //If it exists (does not exist), delete (add) the class named select

9. Complete event processing function
Jquery has already done it for us Various event handling methods are provided. We do not need to write events directly on html elements, but can directly add events to objects obtained through jquery.
For example:

Copy code The code is as follows:

$("#msg") .click(function(){alert(“good”)}) //Added a click event for the element
$(“p”).click(function(i){this.style.color=['# f00','#0f0','#00f'][ i ]})
//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.

Copy code The code is as follows:

//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.

Copy code The code is as follows:

$(document).ready(function(){alert ("Load Success")})

//When the page is loaded, it prompts "Load Success", which is equivalent to the onload event. 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.

Copy code The code is as follows:

//Every time you click, add and delete named names in rotation selected class.
$(“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:

Copy code The code is as follows:

$("p"). bind("click", function(){alert($(this).text());}); //Add a click event for each p element
$("p").unbind(); //Delete all events on all p elements
$("p").unbind("click") //Delete all click events on all p elements

10 , Several practical special effects functions
Among them, the toggle() and slidetoggle() methods provide state switching functions.
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,

Copy code The code is as follows:

$.each( [0,1 ,2], function(i, n){ alert( “Item #” i “: ” n ); });

is equivalent to:

Copy code The code is as follows:

var tempArr=[0,1,2];
for(var i=0;i< ;tempArr.length;i ){
alert(“Item #” i ”: “ tempArr[ i ]);
}

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): Extend an object with one or more other objects and return 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): Delete Whitespace characters at both ends of the string.
For example: $.trim(" hello, how are you? "); //Return "hello, how are you? "
12. Solve conflicts between custom methods or other class libraries 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 together at the same time, variables will be caused. Method definition conflict, Jquery provides a special 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 ';