Understanding Integers and Performance in JS

integers-in-js.md

Understanding Integers and Performance in JS

This is just an interactive node session, not really a code snippet.

But it's pretty instructive.

Implicit Casting

kroberts-macpro:~ kroberts$ node
> 23|0
23
> "23"|0
23
> parseInt("23")
23
> 23.33333|0
23
> "23 cats"
'23 cats'
> "23 cats"|0
0
> parseInt("23 cats")
23
> parseInt("cat");
NaN
> "cat"|0
0

Performance

> console.time('parseInt'); for (var i = 0; i < 10000000; i++) { parseInt('23'); };console.timeEnd('parseInt');
parseInt: 211ms
> console.time('or'); for (var i = 0; i < 10000000; i++) { '23'|0; };console.timeEnd('or');
or: 34ms
> console.time('parseInt'); for (var i = 0; i < 10000000; i++) { parseInt('23'); };console.timeEnd('parseInt');
parseInt: 233ms
> console.time('or'); for (var i = 0; i < 10000000; i++) { '23'|0; };console.timeEnd('or');
or: 33ms
> console.time('parseInt'); for (var i = 0; i < 10000000; i++) { parseInt('23'); };console.timeEnd('parseInt');
parseInt: 232ms
> console.time('or'); for (var i = 0; i < 10000000; i++) { '23'|0; };console.timeEnd('or');
or: 32ms