Solution to "null is null or not an object" in JS

1. 'null' is null or not an object:

<Script type = "text/javascript"> Add the defer = true attribute to it,

That is: <script type = "text/javascript" defer = true>

Defer is used to execute the script after the file is loaded, so that the object cannot be found.

2. document. getElementById is null

Cause: var titab = document. getElementById ("titletab"); no object retrieved
Solution:
1. Add alert (titab) under the error statement to check whether a message box is displayed.
2. If no tab is displayed, check whether the <table> tag of "id = titletab" exists in the HTML code. (Be careful. A letter cannot be wrong)
3. if a tag exists, consider the location of the <script> code segment, remember to include a code similar to getElement. The <script> code segment must appear after the HTML Element. That is to say, you should put the <script> code segment after the

The above two methods can solve the problem .....