Understand $.each and $ (selector).

$.each: This method is used to traverse any collection, including arrays and objects

$ (selector). Each: This method is used to traverse the Jquery object

Syntax: $.each (Obj,callback,args)

① traversing an array

var arry = ["A", "B", "C", "D",...];

$.each (Arry,function (index,value) {...})

callback function: Index stands for an array of indexes , and valuerepresents the values in the array

② traversing Json objects

var json = {key1:value1, key2:value2, key3:value3}

$.each (JSON, function (Key,value) {...})

callback function:key represents the key in the JSON object, value represents the value in the JSON object

③ traversal of jquery objects

var doms = $ ("div"); The//jquery object itself is a collection that can be indexed to convert a jquery object to a DOM object

$.each (Doms, function (Index,value) {..})

callback function: Index stands for jquery Index in object, value stands for jquery object dom objects, also through this get the same dom object

Another way to ③ is $ ("div"). each (function (Index,value) {...})

For the $.each method, you can exit the loop by return false in the callback function if return True is equivalent to the continue in the For loop

question: why Span style= "FONT-FAMILY:CALIBRI;" lang= "en-us" >$ (). each callback function This No jquery Object But dom object

Because $ (). the essence of each method is implemented by calling $.each , by analyzing the $.each source, we can see callback.apply (Object[i++],args ) this piece of code

For$ (). eachPassed in.ObjectIsjquery objects, while object[i++] will jquerydomapply method hijack the properties of the object, then thisdom object

We often see this in the Jquery plugin, through the above analysis, I think I should understand

$.fn.test = function (option) {

Return This.each (function () {// this is a Jquery object

alert (this);// and This is a Dom object

})

}

Understand $.each and $ (selector).