js实现点击下载文件

https://blog.csdn.net/believet93/article/details/99821853
创建a标签设置download属性（filename）自定义事件触发
var a = document.createElement('a') a.download = '' a.href = 'http://' + res.detail.url a.click()

https://developer.mozilla.org/zh-CN/docs/Web/HTML/Element/a
也有类似示例
`var link = document.createElement('a');
link.innerHTML = 'download image';

link.addEventListener('click', function(ev) {
link.href = canvas.toDataURL();
link.download = "mypainting.png";
}, false);

document.body.appendChild(link);`