How jquery determines whether there is a problem with an object

Jquery method to determine whether an object exists: 1. Use the length attribute of the jQuery object to determine if [>0] exists, the code is [ if($("#id")[0]) {} else {}]; 2. Use native Javascript code to judge.

The operating environment of this tutorial: Windows 7 system, jquery version 3.2.1. This method is suitable for all brands of computers.

Jquery method to determine whether an object exists:

Correct use to determine whether an object exists:

if($("#id").length>0){}else{}

Use the length attribute of the jQuery object to determine , exists if >0.

or

 if($("#id")[0]){} else {}

Or directly use the native Javascript code to judge:

 if(document.getElementByIdx_x("id")){} else {}

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