单按钮,执行文件下载和支持多文件下载

单文件下载

var a = document.createElement('a');
a.href = href;
a.download = 'name';
a.click();        

多文件下载

val = ['href','href','href','href']
for (let i = 0; i < val.length; i++) {
	var a = document.createElement("a"), 
      		e = document.createEvent("MouseEvents");
	e.initEvent("click", false, false); //初始化事件对象
	a.href = val[i];
	a.download = ''; 
	a.dispatchEvent(e); //给指定的元素，执行事件click事件
}