Message: 'length' is null or not an object

Webpage error details

User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; InfoPath.3)

Timestamp: Fri, 11 May 2012 06:35:49 UTC

Message: 'length' is null or not an object

Line: 5

Char: 18997

Code: 0

URI: http://server URL/ScriptResource.axd?d=VVc9OziZh0avVAuUDckcZctyzx1FmuIlfTSxpb_QII6eINPFIyFRp05lldCgXiHUGODRhOI7dRH8sB7WoygWB-bvRxVUiAA_CcM0h88Tga5wiu6mXazcz_yOLM3apxrWorI50qlMBWvRPH_z3BQxo-LqLPw1&t=fffffffff9d85fa6

While using the Ajax Toolkit in SharePoint 2010 projects, we observed very strange behaviour of Ajax controls which works in DEV totally, not working in staging in few client machines and few not. very random behaviour. this is because of compression of few script files such as ScriptResource.axd which consumes web service to run script for the Ajax controls to run.
all the error which generates from these ScriptResource.axd can be handled with a simple web config change in all the server of the SharePoint 2010.
I will list few script error that usually come across in SharePoint projects.
If you Google with the error you wont get the solution so easily because the error related to not downloading the script file properly.
Solution:
add this in web config inside  <system.web.extensions>
<system.web.extensions>
<scripting>
  <scriptResourceHandler enableCompression="false" enableCaching="true"/>
</scripting>
</system.web.extensions>
List of common errors from ajax tool kit in SharePoint 2010 environment
Webpage error details on the ie8 laptop.
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 3.0.04506.30; MS-RTC LM 8; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; InfoPath.3)
Timestamp: Mon, 15 Mar 2010 15:52:33 UTC

Message: Invalid character
Line: 1
Char: 1
Code: 0
URI: http://tstsps01/ScriptResource.axd?d=3gtDevuF5hwGxI3DULiHKe4PLpjPC2NBqO_Aln8mJuME3vdMXP1RflDREQe-ARzl4053j1XJPuK_tKVreY7-JEJHhiZGtQfbk53NzX2FfOU1&t=57268015

Message: Invalid character
Line: 1
Char: 1
Code: 0
URI: http://tstsps01/ScriptResource.axd?d=3gtDevuF5hwGxI3DULiHKe4PLpjPC2NBqO_Aln8mJuME3vdMXP1RflDREQe-ARzlKTEXQo2eogcWU5q9nETxLMVv7VkxkeZKcJBd3mhGGIQ1&t=57268015

Message: 'Sys' is undefined
Line: 213
Char: 1
Code: 0
URI: http://tstsps01/Lists/Tasks/AllItems.aspx

Message: 'Sys' is undefined
Line: 1260
Char: 1
Code: 0
URI: http://tstsps01/Lists/Tasks/AllItems.aspx

Message: 'Type' is undefined
Line: 3
Char: 1
Code: 0
URI: http://tstsps01/_layouts/navresizer.js?rev=ulprP4hnQ3FxULueDoY8Vw%3D%3D

Message: 'Type' is undefined
Line: 2
Char: 1
Code: 0
URI: http://tstsps01/_layouts/sp.core.js?rev=hp5jN4e%2BPTRw7LrRxloaGg%3D%3D

Message: 'Type' is undefined
Line: 1
Char: 1
Code: 0
URI: http://tstsps01/_layouts/ScriptResx.ashx?culture=en%2Dus&name=SP%2ERes&rev=CKSAv76LENnzrJqc86tP2g%3D%3D

Message: Object doesn't support this property or method
Line: 2
Char: 132
Code: 0