HTML Collection 转为数组方法

通过Slice进行转换1

var arr = Array.prototype.slice.call( htmlCollection )

通过Slice进行转换2

类似上面的方法

var arr = [].slice.call(htmlCollection);

利用Array.from ES6

Since ECMAScript 2015 there is also Array.from:

var arr = Array.from(htmlCollection);

利用类似Array.from缩写...

ECMAScript 2015 also provides the spread operator, 但Array.from支持map方法，而...不支持

var arr = [...htmlCollection];