How to determine whether an object exists in jquery

Jquery method to determine whether an object exists: You can use the length attribute of the jquery object to determine. If [length>0], it means that the object exists, otherwise it means that the object does not exist, such as [$("# id").length>0].

The operating environment of this tutorial: windows10 system, jquery2.2.4 version. This method is suitable for all brands of computers.

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Jquery method to determine whether an object exists:

The specific method is as follows ;

If the following jQuery code is used to determine whether an object exists, it cannot be used.

if($("#id")){ //... }else{ //... }

Because $("#id") will return object regardless of whether the object exists.

Correct use to determine whether the object exists should be:

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

Use the jQuery object's property length to determine, if > 0, it exists.

or

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

Or directly use the native Javascript code to judge:

if(document.getElementById("id")){ //... }else{ //... }

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