var btns = document.querySelectorAll(".btn");
console.log(btns instanceof Array); // false
btns = Array.prototype.slice.call(btns, 0);
console.log(btns instanceof Array); // true
JS - 把类似document.querySelectorAll(.xxx)、document.getElementsByName(xxx)这种方法的返回结果转换成数组对象...
转载于:https://www.cnblogs.com/andremao/p/9008589.html