Run details:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36
Chrome 100
Windows
Desktop
2 years ago
Test name Executions per second
for let 310.1 Ops/sec
for var 311.3 Ops/sec
for let cached 400.7 Ops/sec
for let cached (const) 408.0 Ops/sec
for var cached 395.5 Ops/sec
forEach 553.5 Ops/sec
Script Preparation code:
x
 
var array = [];
for (var i=0, t=10000; i<t; i++) {
    array.push(Math.round(Math.random() * t))
}
var t=0;
Tests:
  • for let

     
    for (let i = 0; i < array.length; i++) {
      t += array[i];
    }
  • for var

     
    for (var i = 0; i < array.length; i++) {
      t += array[i];
    }
  • for let cached

     
    let len=array.length;
    for (let i = 0; i < len; i++) {
      t += array[i];
    }
  • for let cached (const)

     
    const len=array.length;
    for (let i = 0; i < len; i++) {
      t += array[i];
    }
  • for var cached

     
    var len=array.length;
    for (var i = 0; i < len; i++) {
      t += array[i];
    }
  • forEach

     
    array.forEach(function(v, i) {
      t += v;
    });