Small question about JavaScript operators in DWT code

[sdouglass]

Hi! Like everybody else I'm very excited about your product and have been going over the code, mostly focusing on DWT at first. I've noticed a couple places where there's a JavaScript operator that I've not seen before. For example:

AjxEventMgr.js:
...
59: if (retVal === false)
...

AjxVector.js:
...
34: if (compress !== true)
...

Are those equivalent to "==" and "!=" respectively? If not, how are they different? If so, why use them instead of "==" and "!="?

[KevinH]

The === and !== are identity compares (ie check that things are identical without tye conversion) Some more detail below.






From: http://www.crockford.com/javascript/lint.html



The == and != operators do type coercion before comparing. This is bad because it causes '' == 0 to be true. This can mask type errors.

When comparing to any of the following values, use the === or !== operators, which do not do type coercion.

0 '' undefined null false true

If you want the type coercion, then use the short form. Instead of

(foo != 0)

just say

(foo)

and instead of

(foo == 0)

say

(!foo)

[JeffP]

Check out crockford.com and see his jslint utility to get used to using this operator in your own code. It only took me a couple of times of running my files thru it and I learned the crockford way..