Comments on: If A Then B

By: Eli Grey

Eli Grey — Fri, 09 Apr 2010 02:01:19 +0000

Duncan, here's a profiler I whipped up quickly which also includes sharp scope. Surprisingly, sharp scope performed the worst.

duncanbeevers — Fri, 09 Apr 2010 01:23:39 +0000

Please do let me know if you end up profiling this code.

Eli Grey — Thu, 08 Apr 2010 19:50:41 +0000

It’s likely that if statements can actually be slightly slower when block-scope variables are enabled (by enabling JavaScript 1.7+ for a script).

Case 1:

if (foo) {
  let bar = new FooBar;
  bar.baz(1);
  bar.baz(2);
  foo.bar = bar;
}

Case 2:

var bar;
foo && (
  bar = new FooBar,
  bar.baz(1),
  bar.baz(2),
  foo.bar = bar
)

I haven’t profiled this code yet, but I’m going to assume that the latter is faster in JavaScript 1.7 and higher.