forinobjectkeys.js

function forIn(obj) {
    // for(var i in obj){break;}
    for (var key in obj) {
        var val = obj[key];
        // console.log(key, val);
    }
}

function removeProp(key){
    node.style[key] = null;
}

function setProp(key, value){
    node.style[key] = value;
}

function rm(newStyles, oldStyles) {
    for (var key2 in oldStyles) {
        if (typeof newStyles[key2] === 'undefined') {
            removeProp(key2);
        }
    }

}

var node = document.createElement('div');
function diff(ns, os) {
    var c = 0, k;
    for (k in os)c++;
    for (k in ns) {
        c--;
        if (ns[k] !== os[k]) {
            c--;
            node.style[k] = ns[k];
        }
    }
    if (c !== 0) {
        for (k in os) {
            if (typeof ns[k] === 'undefined') {
                node.style[k] = null;
            }
        }
    }
}

function objectKeys(obj) {
    var keys = Object.keys(obj);
    for (var i = 0; i < keys; i++) {
        var key = keys[i];
        var val = obj[key];
    }
}

function getRandomObj(n) {
    var i = n % 10;
    return i==0?{a:1,b:'23'}:i==1?{b:'1',c:'ds'}:i==2?{c:3,d:'d'}:i==3?{d:'4',e:1}:i==4?{x:1,f:'1'}:i==5?{e:true,d:1}:i==6?{k:7,m:1}:i==7?{fh:5,f:4}:i==8?{sdg:3,x:4}:i==9?{sr:2,f:5}:{ut:5,yy:8};
}

var o = {a: 1, b: '1'};
delete o.a;
// forIn(o);

console.log(diff(getRandomObj(1), getRandomObj(1)));

function abc() {
    console.time('perf');
    for (var i = 0; i < 1e6; i++) {
        // getRandomObj(i)
        // forIn(getRandomObj(i));
        // objectKeys(getRandomObj(i));
        diff(getRandomObj(i), getRandomObj(i));
    }
    console.timeEnd('perf');
}

abc();