JavaScript writted via Script Editor web part does not recognize page elements

Question

In SharePoint 2013 I added a div on a default.aspx like this:

<div id="myDiv"></div>

Then I added a Script Editor web part on the page, and added this JavaScript:

var element = document.getElementById('myDiv');
alert(element);

The alert box displays null. What am I doing wrong?

Answer 1

Make sure the Page is published and approved.

View the page source and make sure the element is present.

Try to place the script inside window.onload event

window.onload = function(){
    var element = document.getElementById('myDiv');
    alert(element);
}