document.getElementsByClassName doesn't work

Question

function getHeight(element) {
    console.log(element);
    var offsetHeight = document.getElementsByClassName(element).offsetHeight;
    console.log(offsetHeight);
         


        

Answer 1

according to documentation https://developer.mozilla.org/en-US/docs/Web/API/document.getElementsByClassName

document.getElementsByClassName(classNames)

returns a collection of html elements (actually instance of HTMLCollection) So If you run this code it should work

    var collection = document.getElementsByClassName(classNames),
      offset = -1;

    if (collection.length > 0) {
      offset = collection[0].offsetHeight;
    }

    return offset;