I was surprised to find that a function call returning a boolean from
a simple test was much (3x!) faster than an associative array
lookup... I was wondering if someone could explain to me how that
could be the case. Is v8 inlining the function somehow, or is the
overhead of a function call extremely low?
Note 1: I'm not complaining, I'm just curious as to how things were
working under the covers.
Note 2: The opposite is true for Firefox, which is 2x slower using the
function call than the associative array... so an optimization for one
would result in a performance regression for another... :(
Example:
------
isWhitespace:function(charCode) {
return charCode == this.spaceCharCode || charCode ==
this.tabCharCode || ... etc ...;
},
for (var i = 0; i < aString.length; i++) {
var isWs = this.isWhitespace(aString.charCodeAt(i));
}
------
Is 3x faster than:
------
whitespace: Associative array mapping whitespace char codes to true,
for (var i = 0; i < aString.length; i++) {
var isWs = this.whitespace[aString.charCodeAt(i)];
}
------
Thanks in advance, Chad
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