Run results for: for in vs Object.keys sort

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.3 Safari/605.1.15

Browser: Safari 15

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
for in	123.5 Ops/sec
Object keys sorted	81.3 Ops/sec

Script Preparation code:



const alpha = 'abcdefghijklmnopqrstuvwxyz';
const keys = [];

for( let i = 0; i < alpha.length; i++ ) {
  for( let j = 0; j < alpha.length; j++ ) {
    for( let k = 0; k < alpha.length; k++ ) {
  		keys.push( alpha[ i ] + alpha[ j ] + alpha[ k ] );
    }
  }
}

function shuffle(array) {
  let currentIndex = array.length,  randomIndex;

  // While there remain elements to shuffle...
  while (currentIndex != 0) {

    // Pick a remaining element...
    randomIndex = Math.floor(Math.random() * currentIndex);
    currentIndex--;

    // And swap it with the current element.
    [array[currentIndex], array[randomIndex]] = [
      array[randomIndex], array[currentIndex]];
  }

  return array;
}

function fill( obj ) {
  shuffle( keys ).forEach( key => {
    obj[ key ] = key;
  } );
  return obj;
}

Tests:

for in
const obj1 = fill( {} ); const obj2 = fill( {} ); let matches = 0; for( const key in obj1 ) { if( obj1[ key ] === obj2[ key ] ) matches++; } console.log( matches );
Object keys sorted
const obj1 = fill( {} ); const obj2 = fill( {} ); const obj1Keys = Object.keys( obj1 ).sort(); const obj2Keys = Object.keys( obj2 ).sort(); const numKeys = obj1Keys.length; let matches = 0; for( let i = 0; i < numKeys; i++ ) { if( obj1[ obj1Keys[ i ] ] === obj2[ obj2Keys[ i ] ] ) matches++; } console.log( matches );

Run results for: for in vs Object.keys sort

for in

Object keys sorted