var arr = ['j','s','从','数','组','中','随','机','取','出','一','个','元','素'];
var item = arr[Math.floor(Math.random()*arr.length)];
console.log(item);
var arr = ['j','s','从','数','组','中','随','机','取','出','一','个','元','素'];
var item = arr[Math.floor(Math.random()*arr.length)];
console.log(item);