How can I check if an element exists in the DOM using JavaScript?

General Discussions
3

Nice one, @tim-khorev !

Another approach I’ve used a lot is document.getElementsByClassName(). If you’re dealing with multiple elements that share the same class, this method can be especially handy. It returns a live HTMLCollection, meaning if the DOM changes, the collection is automatically updated.

window.onload = function() {
    var elements = document.getElementsByClassName("demo-class");
    if (elements.length > 0) {
        console.log("Element exists");
    } else {
        console.log("Element does not exist");
    }
};

This approach works well when you’re expecting to find several elements. Just check the length property—if it’s greater than 0, you know the element(s) are there.