The Extend extension method of jquery

jquery's Extend extension method:
The extended method of jquery extend is a common method in the process of writing plug-ins, there are some overloaded prototypes, here we go to understand.
One, jquery extension method prototype is:　　　

Extend (dest,src1,src2,src3 ...);

It means to src1,src2,src3 ... Merged into Dest, the return value is the merged dest, which shows that the method is modified to dest structure after merging. If you want to get the results of a merge but do not want to modify the structure of the dest, you can use the following:

var newsrc = $.extend ({},src1,src2,src3 ...)//That is, "{}" as the Dest parameter.

This can be src1,src2,src3 ... To merge, and then return the merge results to NEWSRC. The following example:

var result = $.extend ({},{name: "Tom", age:21},{name: "Jerry", Sex: "Boy"})

Then the combined results

result = {Name: "Jerry", age:21, Sex: "Boy"}

That is, if the following argument has the same name as the previous argument, then the previous parameter value will be overwritten.

ii. omitting dest parameters
The Dest parameter in the above extend method prototype can be omitted, and if omitted, the method can have only one src parameter, and the SRC is merged into an object that invokes the Extend method, such as:
1, $.extend (SRC)
The approach is to merge SRC into the global object of jquery, such as:

$.extend ({hello:function () {alert (' Hello ');}});

is to incorporate the Hello method into the global object of jquery.
2, $.fn.extend (SRC)
This method merges src into the instance object of jquery, such as:

$.fn.extend ({hello:function () {alert (' Hello ');}});

is to merge the Hello method into the instance object of jquery.

The following example illustrates several common extension instances:

$.extend ({net:{}});

This is the extension of a net namespace in the jquery global object.

$.extend ($.net,{hello:function () {alert (' Hello ');}})

This is to extend the Hello method to the net namespace of the previously extended jquery.

three, jquery extend method also has an overloaded prototype:

Extend (BOOLEAN,DEST,SRC1,SRC2,SRC3 ...)

The first argument Boolean represents whether to make a deep copy, the rest of the arguments are consistent with the previous description, and what is called a deep copy, let's look at an example:

var result = $.extend (true, {}, {name: John), location: {City: Boston, County: ' USA '}}, {last: ' Resig ', Location: {state: "MA", County: "" "});

We can see that the nested SRC1 in the location:{city: "Boston"},SRC2 also have nested objects location:{state: "MA"}, the first depth copy parameter is true, then the result of the merge is:

result = {name: ' John ', Last: ' Resig ', location:{city: "Boston", State: "MA", County: "" "}}

That is, it merges the nested subforms in SRC, and if the first argument is false, let's see what the result of the merge looks like:

var result = $.extend (false, {}, {name: "John", location:{city: "Boston", County: "The USA"}}, {last: "Resig", Location: {state: "MA", County: "" "});

Then the result of the merger is:

result = {name: ' John ', Last: "Resig", Location:{state: "MA", County: "" "}

Above are some of the details that $.extend () often uses in the project.