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@bjouhier bjouhier/bench.js
Created Feb 13, 2012

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Simple bench of basic JS constructs
function bench(name, fn) {
var result;
// 2 passes to let V8 optimize
for (var pass = 2; pass >= 0; pass--) {
var count = 1;
while (true) {
var t0 = Date.now();
fn(count);
dt = (Date.now() - t0);
if (dt > 100) {
result = Math.round(dt * 1000 * 1000 / count);
break;
}
count *= 2;
}
}
console.log(name + "\t" + result + "ns");
}
var DIGITS = "0123456789";
bench(";", function(count) {
for (var i = count; i > 0; i--) {;
}
})
bench("x++", function(count) {
var x = 0;
for (var i = count; i > 0; i--) {
x++;
}
})
bench("f()", function(count) {
function f() {};
for (var i = count; i > 0; i--) {
f();
}
})
bench("f(1,2,3)", function(count) {
function f() {};
for (var i = count; i > 0; i--) {
f(1, 2, 3);
}
})
bench("f.call(this)", function(count) {
function f() {};
for (var i = count; i > 0; i--) {
f.call(this);
}
})
bench("f.apply(this, [])", function(count) {
function f() {};
var arr = [];
for (var i = count; i > 0; i--) {
f.apply(this, arr);
}
})
bench("{}", function(count) {
for (var i = count; i > 0; i--) {
var foo = {};
}
})
bench("{a:1,b:2,c:3}", function(count) {
for (var i = count; i > 0; i--) {
var foo = {
a: 1,
b: 2,
c: 3
};
}
})
bench("new", function(count) {
for (var i = count; i > 0; i--) {
var foo = new Object();
}
})
bench("[]", function(count) {
for (var i = count; i > 0; i--) {
var foo = [];
}
})
bench("[1,2,3]", function(count) {
for (var i = count; i > 0; i--) {
var foo = [1, 2, 3];
}
})
bench("try/catch", function(count) {
for (var i = count; i > 0; i--) {
try {} catch (ex) {}
}
})
bench("try/finally", function(count) {
for (var i = count; i > 0; i--) {
try {} finally {}
}
})
bench("new Error()", function(count) {
for (var i = count; i > 0; i--) {
new Error();
}
})
Error.stackTraceLimit = 0;
bench("new Error() no stack", function(count) {
for (var i = count; i > 0; i--) {
new Error();
}
})
bench("random", function(count) {
for (var i = count; i > 0; i--) {
Math.random();
}
})
bench("exp(2.1)", function(count) {
for (var i = count; i > 0; i--) {
Math.exp(2.1);
}
})
bench("s.length", function(count) {
for (var i = count; i > 0; i--) {
DIGITS.length;
}
})
bench("s[0]", function(count) {
for (var i = count; i > 0; i--) {
DIGITS[0];
}
})
bench("s.charCodeAt(0)", function(count) {
for (var i = count; i > 0; i--) {
DIGITS.charCodeAt(0);
}
})
bench("/\d+/.exec(s)", function(count) {
for (var i = count; i > 0; i--) {
/\d+/.exec(DIGITS);
}
})
bench("RE.exec(s)", function(count) {
var RE = /\d+/;
for (var i = count; i > 0; i--) {
RE.exec(DIGITS);
}
})
bench("RE capture", function(count) {
var RE = /(\d+)/;
for (var i = count; i > 0; i--) {
RE.exec(DIGITS);
}
})
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