jonIt’s 2015, and from time to time I still see a lot of == peppered throughout codebases that I work with, and just wanted to share a few posts that might change your mind =)
tl;dr;
=== and its complement !== and should be used like 99% of the time because it is faster and more accurate.
- http://stackoverflow.com/questions/359494/does-it-matter-which-equals-operator-vs-i-use-in-JavaScript-comparisons
- http://stackoverflow.com/questions/2401478/why-is-faster-than-in-php/3333581
- http://jsperf.com/comparison-of-comparisons
> 0 == "0"
< true
> 0 === "0"
< false
> 0 == false
< true
> "0" == false // really?
< true
> !!"0"
< true
> !"0"
< false
> "0" === false
< false
There are more perverse and mind-bending examples that are out there, but I’ll leave you with those for now.
As you can see, the former == does type coercion, which is lazy way of doing comparisons without casting data explicitly, and can find yourself in hot water down the line. The latter === does type checking first, and then checks equality of the values.
Protip #1: If you want to test a JS expression or figure out some syntax really quickly, just open your JS console in the browser inspect tool.
Protip #2: If testing for something truthy or falsy, a nice trick is to just do use the ! operator twice (!!). As can be seen above, JS treats non-empty strings as a truthy (yet, strangely, "0" == false)