Encodes text and merge field values for use in JavaScript by inserting escape characters, such as a backslash (\), before unsafe JavaScript characters, such as the apostrophe (').
Use
{!JSENCODE(text)} and replace
text with the merge field or text string that contains the unsafe JavaScript
characters.
Tips
This function is only available in custom buttons and links, and in Visualforce.
Merge Field Example
If the merge field foo__c contains <B>Enter the user's name<b>, {!JSENCODE(foo__c)} results in: \u003CB\u003EEnter the
user\'s name\u003C\/b\u003E