testPerf.js

const test = ( f, _n ) => {
    console.log( ( new Array( _n || 1000 ) ).fill( 0 ).map( n => {
        let t0 = performance.now()
        f()
        let t1 = performance.now()
        return t1 - t0
    } ).reduce( ( sum, d ) => sum+=d ) + ' ms' )
}


let tmp, someNumbers = [1,2,3,4,5,6,7,8,9,10];

const forLoop = () => {
    for( var i = 0; i < someNumbers.length; i ++ ){
        tmp = someNumbers[ i ];
    }
}

const inverseForLoop = () => {
    for( var i = someNumbers.length-1; i >= 0; i -- ){
        tmp = someNumbers[ i ];
    }
}

const forOfLoop = () => {
    for( let num of someNumbers ){
        tmp = num;
    }
}

const forEachLoop = () => {
    someNumbers.forEach( n => tmp = n )
}

test( forLoop )
test( inverseForLoop )
test( forOfLoop )
test( forEachLoop )