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  • FileReader 对象

    FileReader 实例中有四个方法来读取文件数据

    1、readAsBinaryString(Blob|File)

    2、readAsDataURL(Blob|File) 

    3、readAsText(Blob|File)

    4、readAsArrayBuffer(Blob|File)

    FileReader 实例包含很多事件(onerror, onprogress, onload[result])

    <input name="file" id="uploadFile" />
    
    var file = document.getElementById("uploadFile");
    var bufferSize = 1024;
    var pos = 0;
    
    var onload = function(e) {
         console.log("Read", e.target.result);
         var img = document.createElement("img");
         img.src = e.target.result;
         img.width = 300;
         img.height = 300;
         document.body.appendChild(img);
    };
    
    var onerror = function() {}
    
    var onprogress = function(e) {}
    
    file.onchange = function() {
         if (file.files) file = file.files[0];
         while (pos < file.size) {
            var reader = new FileReader();
            reader.onload = onload;
            reader.onerror = onerror;
            /*reader.readAsText(file.slice(pos, bufferSize));
            pos += bufferSize; */
           
            reader.readAsDataURL(file);
            pos = file.size + 1;
         }
               
    }
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  • 原文地址:https://www.cnblogs.com/zhoulingfeng/p/4313539.html
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