Javascript Array length performance comparison
By caching the length of array's length we can save up in some times quite a lot of miliseconds. This is useful specially in cases where algorithm performance is critical.
var l = [];
for (let i=0; i<10000; i++) {
l.push(i);
}
let start = performance.now();
// no length caching
for (let j=0; j<l.length; j++) {
l[j] += 1; // simple
}
let end = performance.now();
let total = end-start;
console.log(total);
//caching length
start = performance.now();
for (let j=0, x = l.length; j<x; j++) {
l[j] += 1; // simple
}
end = performance.now();
total = end-start;
console.log(total);
First measure and second measure:
0.6850000000001728
0.2849999999998545
Written by Esteban
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