uniapp H5保存base64图片方法

savePicture(base64) {
	// var arr = base64.split(','); //可以这样去掉data:image/png;base64,只拿，号后面部分  
	var bytes = atob(base64)  
	let ab = new ArrayBuffer(bytes.length);  
	console.log(ab)  
	let ia = new Uint8Array(ab);  
	for (let i = 0; i < bytes.length; i++) {  
		ia[i] = bytes.charCodeAt(i);  
	}  
	var blob = new Blob([ab], { type: 'application/octet-stream' });  
	var url = URL.createObjectURL(blob);  
	var a = document.createElement('a');  
	a.href = url;  
	a.download = new Date().valueOf() + ".jpg";  
	var e = document.createEvent('MouseEvents');  
	e.initMouseEvent('click', true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);  
	a.dispatchEvent(e);  
	URL.revokeObjectURL(url);  
},