Is there an “exists” function for jQuery?

Question

How can I check the existence of an element in jQuery?

The current code that I have is this:

if ($(selector).length > 0) {
    // Do something
}
<         


        

Answer 1

No need for jQuery (basic solution)

if(document.querySelector('.a-class')) {
  // do something
}

Much more performant option below(notice lack of a dot before a-class).

if(document.getElementsByClassName('a-class')[0]) {
  // do something
}

querySelector uses a proper matching engine like $() (sizzle) in jQuery and uses more computing power but in 99% cases will do just fine. The second option is more explicit and tells the code exactly what to do. It's much faster according to jsperf https://jsperf.com/getelementsbyclassname-vs-queryselectorall/25