Javascript String Compare == sometimes fails

Question

How could the following code sometimes evaluate to false?

(transport.responseText == \'1\' || 
 transport.responseText == \'CARD_VALID\')

M

Answer 1

Try using === to match exactly (type and value). This is the recommended comparison operator in javascript.

Check the datatypes of the strings to make sure, and look for hidden unicode or control characters in both strings.