jq压缩图片base64转成file上传到服务器

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

    </head>
    <body>
        <input type="file" id="picFile" onchange="readFile(this)" />
        <img style="" id="img" src="" alt="" />
        <script src="https://cdn.bootcss.com/jquery/3.4.1/jquery.min.js"></script>
        <script language="javascript">
            function readFile(obj){
                maxSize = 2*1024*1024;
                var file = obj.files[0];  
                if(file.size < maxSize){
                    alert('小于2m直接上传');
                    upload(file);
                    return false
                }
                console.log(file)
                //判断类型是不是图片
                if(!/image\/\w+/.test(file.type)){
                  alert("请确保文件为图像类型");
                  return false;
                }
                var reader = new FileReader();
                reader.readAsDataURL(file);
                reader.onload = function(e){
                    dealImage(this.result,{width:750},function(base){
                        document.getElementById('img').setAttribute('src',base)
                        var file = dataURLtoFile(base,'test.jpg')
                        upload(file);
                    });
                }
            }


            function upload(file)
            {
                var formData = new FormData();
                    formData.append('img_url', file);
                    $.ajax({
                            url: 'http://127.0.0.1/h5_upload.php',
                            type: 'POST',
                            cache: false,
                            data: formData,
                            dataType: "JSON",
                            processData: false,
                            contentType: false,
                            success: (res) => {
                                console.log(res)

                            }
                        }).done(function(res) {
                        }).fail(function(res) {
                        });
            }

            //base64 转 file
            //filename 上传文件名(需含扩展名)
            function dataURLtoFile(dataurl, filename) {
                var arr = dataurl.split(','), mime = arr[0].match(/:(.*?);/)[1],
                bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);
                while(n--){
                    u8arr[n] = bstr.charCodeAt(n);
                }
                return new File([u8arr], filename, {type:mime});
            }

            /* 图片压缩,默认同比例压缩
             * @param {Object} path
             * pc端传入的路径可以为相对路径,但是在移动端上必须传入的路径是照相图片储存的绝对路径
             * @param {Object} obj
             * obj 对象 有 width, height, quality(0-1)
             * @param {Object} callback
             * 回调函数有一个参数,base64的字符串数据
             */
            function dealImage(path, obj, callback){
               var img = new Image();
               img.src = path;
               img.onload = function(){
                   var that = this;
                   // 默认按比例压缩
                   var w = that.width,
                   h = that.height,
                   scale = w / h;
                   w = obj.width || w;
                   h = obj.height || (w / scale);
                   var quality = 1; // 默认图片质量为0.7
                   console.log(w,h)

                   var canvas = document.createElement('canvas');//生成canvas
                   var ctx = canvas.getContext('2d');
                   // 创建属性节点
                   var anw = document.createAttribute("width");
                   anw.nodeValue = w;
                   var anh = document.createAttribute("height");
                   anh.nodeValue = h;
                   canvas.setAttributeNode(anw);
                   canvas.setAttributeNode(anh);
                   ctx.drawImage(that, 0, 0, w, h);
                   // 图像质量
                    if(obj.quality && obj.quality <= 1 && obj.quality > 0){
                        quality = obj.quality;
                    }
                   // quality值越小,所绘制出的图像越模糊
                   var base64 = canvas.toDataURL('image/jpeg', quality );
                   // 回调函数返回base64的值
                   callback(base64);
               }
            }
        </script>
    </body>
</html>
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