IE10的readAsBinaryString的替代项

我在这里找到了答案：

var binary = "";
var bytes = new Uint8Array(buffer);
var length = bytes.byteLength;
for (var i = 0; i < length; i++) {
  binary += String.fromCharCode(bytes[i]);
}

根据David Jones的回答，我编写了这个方法。try/catch处理IE10/11中的readAsBinaryString异常，并将自己称为"IE模式"：

function readBinaryStringFromBlob(blob, callback, ie) {
    var reader = new FileReader();
    if(!ie) {
        reader.addEventListener("loadend", function () {
            callback(reader.result);
        });
        try {
            reader.readAsBinaryString(blob);
        } catch (err) {
            readBinaryStringFromBlob(blob, callback, true);
        }
    } else {
        reader.addEventListener("loadend", function () {
            var binary = "";
            var bytes = new Uint8Array(reader.result);
            var length = bytes.byteLength;
            for (var i = 0; i < length; i++) {
                binary += String.fromCharCode(bytes[i]);
            }
            callback(binary);
        });
        reader.readAsArrayBuffer(blob);
    }
}

如果你想要一个更简洁、ES2015的东西，那么这可能就是你想要的：

  const reader = new FileReader();
  reader.onerror = e => alert("File cannot be opened");
  if (reader.readAsBinaryString) {
     reader.onload = e => alert(e.target.result));
     reader.readAsBinaryString(file);
  }
  else {
     // Catering for IE 10/11
     reader.onload = e => {
        const bytes = new Uint8Array(e.target.result);
        const binary = bytes.reduce((acc, byte) => acc + String.fromCharCode(byte), "");
        alert(binary);
     };
     reader.readAsArrayBuffer(file);
  }

试试我的代码：

    function readAsBinaryString(blob, callback) {
        var reader = new FileReader();
        var binStringCallback = function (e) {
            callback(e.target.result);
        };
        var arrBufferCallback = function (e) {
            var binary = "";
            var bytes = new Uint8Array(e.target.result);
            var length = bytes.byteLength;
            for (var i = 0; i < length; i++) {
                binary += String.fromCharCode(bytes[i]);
            }
            callback(binary);
        };
        reader.onerror = reader.onabort = function () {
            callback(null)
        };
        if (typeof reader.readAsBinaryString != "undefined") {
            reader.onload = binStringCallback;
            reader.readAsBinaryString(blob);
        } else {
            reader.onload = arrBufferCallback;
            reader.readAsArrayBuffer(blob);
        }
    }