如何在没有 FileReader 的情况下从 Blob 和 File 对象创建 ArrayBuffer 和数据 URI？

Question

This Question is related to and inspired by How to updoad in old browsers (ex Safari 5.1.4)此问题与如何在旧浏览器（例如 Safari 5.1.4）中升级有关并受其启发

Given an <input type="file"> element having a files property containing File objects which inherit from Blob , is it possible to create a ArrayBuffer and convert the ArrayBuffer to a data URI from a Blob or File object without using FileReader ?给定一个<input type="file">元素，该元素的files属性包含从Blob继承的File对象，是否可以创建一个ArrayBuffer并将ArrayBuffer转换为Blob或File对象中的data URI而不使用FileReader ？

Approaches have tried so far have been到目前为止已经尝试过的方法是

create a mock WebSocket with .binaryType set to "arraybuffer" , create a MessageEvent with event.data set to File object;创建一个.binaryType设置为"arraybuffer"的模拟WebSocket ，创建一个MessageEvent并将event.data设置为File对象； result is File object at onmessage handler结果是onmessage处理程序中的File对象
set prototype of File to ArrayBuffer , Uint8Array ;将File原型设置为ArrayBuffer ， Uint8Array ； result is Uncaught TypeError: Method ArrayBuffer.prototype.byteLength called on incompatible receiver #<ArrayBuffer>() , Uncaught TypeError: Method get TypedArray.prototype.byteLength called on incompatible receiver [object Object]()结果是Uncaught TypeError: Method ArrayBuffer.prototype.byteLength called on incompatible receiver #<ArrayBuffer>() ， Uncaught TypeError: Method get TypedArray.prototype.byteLength called on incompatible receiver [object Object]()
set File at FormData object, attempt to post request body to <iframe> , admittedly not well-conceived;在FormData对象上设置File ，尝试将请求正文发布到<iframe> ，诚然构思不佳； result Bad Request at plnkr结果plnkr 的Bad Request

Expected result: Convert Blob and File objects to TypedArray then to data URL , or directly to data URL预期结果：将Blob和File对象转换为TypedArray然后转换为data URL ，或直接转换为data URL

<!DOCTYPE html>
<html>

<head>
</head>

<body>
  <form method="get" entype="multipart/form-data" target="binaryFrame">
    <input id="#avatar" type="file" name="file" />
    <input type="submit" />
  </form>
  <iframe name="binaryFrame"></iframe>
  <script>
    var input = document.querySelector("input[type=file]");
    input.addEventListener("change", handleFiles, true);
    // see http://jsfiddle.net/adamboduch/JVfkt/
    var sock = new WebSocket("ws://mock");
    sock.binaryType = "arraybuffer";
    sock.onerror = function(e) {
        console.log("sock error", e); // ignore, here
      }

    sock.onmessage = function(e) {
      console.log("socket message", e.data, e.data instanceof ArrayBuffer);
    };

    function handleFiles(evnet) {
      var file = event.target.files[0];
      sock.dispatchEvent(new MessageEvent("message", {
        data: file
      }));
      var data = new FormData();
      data.append("file", file);
      document.forms[0].action = data;
    }
  </script>
</body>

</html>

See also Display image from blob using javascript and websockets , How can you encode a string to Base64 in JavaScript?另请参阅使用 javascript 和 websockets 显示 blob 中的图像，如何在 JavaScript 中将字符串编码为 Base64？ ; ; interestingly ironic as am now asking similar Question https://stackoverflow.com/questions/34302231/is-there-any-way-to-convert-the-file-to-an-arraybuffer-without-filereader-api ;有趣的是具有讽刺意味，因为我现在问类似的问题https://stackoverflow.com/questions/34302231/is-there-any-way-to-convert-the-file-to-an-arraybuffer-without-filereader-api ； Blob .slice() method , FileReader .readAsDataURL() method Blob .slice()方法、 FileReader .readAsDataURL()方法

Answer 1

I just put it here:我只是把它放在这里：

 var input = document.querySelector("input[type=file]"); input.addEventListener("change", handleFiles, true); // for url window.URL = window.URL || window.webkitURL; function handleFiles(evnet) { var file = event.target.files[0]; document.querySelector('iframe') .setAttribute('src', window.URL.createObjectURL(file)); }

 <!DOCTYPE html> <html> <head> </head> <body> <form method="get" entype="multipart/form-data" target="binaryFrame"> <input id="#avatar" type="file" name="file" /> <input type="submit" /> </form> <iframe name="binaryFrame"></iframe> </body> </html>

如何在没有 FileReader 的情况下从 Blob 和 File 对象创建 ArrayBuffer 和数据 URI？

问题描述

1 个解决方案

解决方案1
1 2020-12-30 01:34:07

如何在没有 FileReader 的情况下从 Blob 和 File 对象创建 ArrayBuffer 和数据 URI？

问题描述

1 个解决方案

解决方案1 1 2020-12-30 01:34:07

解决方案1
1 2020-12-30 01:34:07