The difference between document.getElementById method in Firefox and IE_javascript skills

[Key points] The difference between document.getElementById method in Firefox and IE.
As follows, there is a text control with name="txtVersion":

According to the above information, we need to use JS to get the value in its control. We write like this:
var strVersion= document.getElementById("txtVersion").value;
The above writing method does not work Wrong, it is correct in browsers with IE as the core, but Firefox has very strict requirements on this, and the above code cannot pass. In Firefox, when using the document.getElementById method, be sure to add the id="txtVersion" attribute to the control, as follows: