How to determine whether an object exists in jQuery

Objects are very important in both php and js. In this article, we mainly share with you the method of determining whether an object exists in jQuery. We hope it can help everyone.

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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