something

var colors=['red','green','yellow'];

console.log(colors)//['red','green','yellow']

console.log(colors.toString());//red,green,yellow

console.log(colors.valueOf());//['red','green','yellow']

console.log(colors.toLocaleString());//red,green,yellow

function num(nums){

　　if(nums<=1){

　　　　return 1;

　　}

　　else{

　　　　return nums*num(nums-1);

　　}
}

console.log(nums(5));//120递归函数