Possible cases for Javascript error: "Expected identifier, string or number"

The cause of this type of error can often be a misplaced comma in an object or array definition:

var obj = {
   id: 23,
   name: "test",  <--
}

If it appears at a random line, maybe it's part of an object defintion you are creating dynamically.

Using the word class as a key in a Javascript dictionary can also trigger the dreaded "Expected identifier, string or number" error because class is a reserved keyword in Internet Explorer.

BAD

{ class : 'overlay'} // ERROR: Expected identifier, string or number

GOOD

{'class': 'overlay'}

When using a reserved keyword as a key in a Javascript dictionary, enclose the key in quotes.

Hope this hint saves you a day of debugging hell.