I found many questions concerning form elements that are null but I simply can‘t get this to work.
It works in every browser but when it‘s embedded in WordPress it stops working in Firefox.
The Firefox-Console says I should use document.getelementbyid but in every way I try it, Firefox says the form is null or that “myform is not defined”.
Can you post the html and javascript code? my first guess is that you didn’t give the form or input an id attribute. For example
<input name="myInput" type="text" />will not work for
document.getElementById("myInput").You need to add the id attribute like so