Ultimate string concatenation tests

JavaScript performance comparison

Revision 7 of this test case created by Rod Knowlton

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
Length and join
var array = [];
for (var i = 0; i < 100; i++) {
 array[array.length] = "foo";
}

var str = array.join("");
pending…
Push and join
var array = [];
for (var i = 0; i < 100; i++) {
 array.push("foo");
}

var str = array.join("");
pending…
String +=
var str = "";
for (var i = 0; i < 100; i++) {
 str += "foo";
}
pending…
Concat
var str = "";
for (var i = 0; i < 100; i++) {
 str = str.concat("foo");
}
pending…
Push and concact
var array = [];
for (var i = 0; i < 100; i++) {
 array.push("foo");
}

var str = String.prototype.concat.apply("", array)
pending…
Hotspot Test (based on http://my.opera.com/emoller/blog/2011/05/01/javascript-performance)
var dest = 'foo';
while (dest.length < 300) {
 var offs = dest.length - 3;
 for (var i = offs; i < offs + 6; ++i)
 dest += dest[i];
}
pending…
@rem's Hotspot (http://jsbin.com/aruze3/edit)
var dest = 'foo'.split(''); // turn it in to an array
var start = new Date();
while (dest.length < 300) {
 var offs = dest.length - 3;
 for (var i = offs; i < offs + 6; ++i)
 dest.push(dest[i]); // push on to the array, instead of concat
 // dest += dest[i];
}
var str = dest.join("");
pending…
w/o concat of substring of self
var dest = 'foo';
var other = 'foo';
while (dest.length < 300) {
 var offs = dest.length - 3;
 for (var i = offs; i < offs + 6; ++i)
 dest += other[i % 3];
}
pending…
@rem's w/o concat of substring of self
var dest = 'foo'.split(''); // turn it in to an array
var other = 'foo';
var start = new Date();
while (dest.length < 300) {
 var offs = dest.length - 3;
 for (var i = offs; i < offs + 6; ++i)
 dest.push(other[i] % 3); // push on to the array, instead of concat
 // dest += dest[i];
}
var str = dest.join("");
pending…

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