How to determine whether an object is a jquery object

Method to determine whether an object is a jQuery object: Use [obj instanceof jQuery] to determine, the code is [if (obj instanceof jQuery){alert("This is a jQuery object");}].

The operating environment of this tutorial: windows10 system, jquery2.2.4, this article is applicable to all brands of computers.

Method to determine whether an object is a jquery object:

When we use jquery's each to do loop traversal, we often use this, and sometimes we I don't know what this refers to, because in order to use jquery's method, the object must be a jquery object.

In addition, to determine the type of a JavaScript object, you can use typeof, but typeof can only determine the basic object of js (string, boolean, number, object).

Determine an object Whether it is a jquery object, you can use obj instanceof jQuery

var obj = $("div");
if (obj instanceof jQuery) {
    alert("这是一个jQuery对象");
} else {
    alert("这是一个其它对象")
}
 
obj.each(function() {
    console.log(this instanceof jQuery); //false
    console.log($(this) instanceof jQuery); //true
})

Others:

• ##$(this)[0]

• $(this).get(0)

• ##$(this).toArray()[ 0];

The above three writing methods are equivalent

It is not conversion, it is to obtain the internal DOM object reference.

jQuery has There are 2 cores, one is a query and the other is a method plug-in

$('..')

is a factory method that calls the query internally (according to the css positioning method to obtain all dom references that meet the conditions , there are other special circumstances) And return a jQuery object. This object is an extended Array. All queried DOM are placed in this Array.

then

get(index )

The internal code is return this[index]

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