Implicit/Explicit type conversion
JavaScript performance comparison
Test case created by Kyle Simpson
Info
Want to test the effects of using variable values that must be implicitly type-coerced versus explicitly coercing them.
Preparation code
<script>
var num_1 = 10;
var num_2 = "10";
var result_1, result_2, i;
</script>
Test runner
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Java applet disabled.
Testing in unknown unknown
| Test |
Ops/sec |
implicit coercion required |
result_1 = "";
result_2 = 0;
for (i = 0; i < 10000; i++) {
result_1 += num_1; // 10 will be auto-coerced to "10"
result_2 += (num_2 - 0); // "10" will be auto-coerced to 10
}
|
pending… |
no coercion required |
result_1 = 0;
result_2 = "";
for (i = 0; i < 10000; i++) {
result_1 += num_1; // no coercion required
result_2 += num_2; // no coercion required
}
|
pending… |
explicit coercion |
result_1 = "";
result_2 = 0;
for (i = 0; i < 10000; i++) {
result_1 += String(num_1); // 10 explicitly coerced to "10"
result_2 += +num_2; // "10" explicitly coerced to 10
}
|
pending… |
explicit coercion #2 |
result_1 = "";
result_2 = 0;
for (i = 0; i < 10000; i++) {
result_1 += String(num_1); // 10 explicitly coerced to "10"
result_2 += ~~num_2; // "10" explicitly coerced to 10
}
|
pending… |
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