js技巧

1.循环数组

--------从0开始----------

var index = -1;
var arr = [8,99,44,22,7];
while(++index < arr.length){
    console.log(arr[index])
}
---------从后开始---------
var length = arr.length;
while(length--){
    console.log(arr[length])
}
--------------------

2.跳出循环

var iNum = 0;
var inum = 0;
outermost:
    for (var i = 0; i < 4; i++) {
        for (var j = 0; j < 4; j++) {
            if (i == 2 && j == 2) {
                break outermost;
            }
            iNum++;
        }
        inum++;
    }
console.log(iNum,inum);    //10 2
//---------------------------------------------
var Num = 0;
var num = 0;
outer:
    for (var i = 0; i < 4; i++) {
        for (var j = 0; j < 4; j++) {
            if (i == 2 && j == 2) {
                continue outer;
            }
            Num++;
        }
        num++;
    }
console.log(Num,num);    //14 3