W3c error on asp.net pages due to script tag on page?

certain times we put javascript on the page itself. but putting javascript on the page gives w3c validation error.
solution for this is

GetDocumentById problem in javascript using masterpage

Many times you have faced a problem that you were not able to find the control which is there on ur page using document.getElementById("").
The solution for this problem is use document.getElementByID("")