SOURCE

var start = new Date().getTime(); //起始时间
    var items = [1, 2, 3];
    var reducer = function add(sumSoFar, item) { return sumSoFar * 10 + item; };
    var total = items.reduce(reducer, 0);
    console.log(total);
    var obj = { a: 'a' };
    //obj.values()
    console.log(Object.keys(obj));
    提前终止forEach,可以改用every，返回false时就是break
    items.forEach((one) => {
    	console.log(one)
        if (one == 2) {
            items.length = 0;
        }
    })
    items.every((i) => {
        if (i == 2) return false;
        console.log(i);
        return true;
    });
    items.some(function(i) {
        if (i == 2) return true;
        console.log(i);
    });
    console.log(items)
    var end = new Date().getTime(); //接受时间     
    console.log((end - start) + "ms");