用QRCode.js制作二维码解析器（qrcode.decode方法解析二维码）

<script src="llqrcode.js" type="text/javascript" charset="utf-8"></script>

//获取图片路径
let getObjectURL = function(file){
    let url = null ; 
    if (window.createObjectURL!=undefined) { // basic
        url = window.createObjectURL(file) ;
    } else if (window.URL!=undefined) { // mozilla(firefox)
        url = window.URL.createObjectURL(file) ;
    } else if (window.webkitURL!=undefined) { // webkit or chrome
        url = window.webkitURL.createObjectURL(file) ;
    }
    return url ;
}

url = getObjectURL(elem.files[0]);

qrcode.decode(url);

qrcode.callback = function(imgMsg){
	fn(imgMsg,url);
}