For Loop vs. Optimized For Loop

JavaScript performance comparison

Revision 33 of this test case created

Info

A speed comparison between for loops.

Preparation code

<a href="#">Test</a>
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<a href="#">Test</a>
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<a href="#">Test</a>
<a href="#">Test</a>
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Preparation code output

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Testing in unknown unknown
Test Ops/sec
i--
var anchors = document.getElementsByTagName("a");

for (var i = anchors.length - 1; i >= 0; i --) {
  anchors[i].style.color = "red";
}
pending…
Optimized For Loop
var anchors = document.getElementsByTagName("a");

for (var i = anchors.length - 1; i >= 0; i -= 1) {
  anchors[i].style.color = "red";
}
pending…
Optimized While Loop
var anchors = document.getElementsByTagName("a"),
    i = anchors.length;

while (i--) {
  anchors[i].style.color = "red";
}
pending…
Optimize Do While Loop
var anchors = document.getElementsByTagName("a"),
    i = anchors.length - 1;

do {
  anchors[i].style.color = "red";
}
while (i--);
pending…

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