以编程方式设置type =" file"的值。输入HTML元素？ [英] Programmatically set the value of a type="file" input HTML element?

问题描述

注意：

下面的答案反映了2009年旧版浏览器的状态。现在您可以在2017年使用JavaScript动态/编程地设置文件输入元素的值。

The answer(s) below reflect the state of legacy browsers in 2009. Now you can actually set the value of the file input element dynamically/programatically using JavaScript in 2017.

有关详细信息和演示，请参阅此问题的答案：
如何以编程方式设置文件输入值（即：拖放文件时）？

See the answer in this question for details as well as a demo:
How to set file input value programatically (i.e.: when drag-dropping files)?

我需要做的是以编程方式从使用.NET WebBrowser的应用程序的javascript代码向服务发送POST请求，基本上是一个嵌入式Internet Explorer。此服务要求其中一个字段为文件。

What I need to do is to programmatically send a POST request to a service from javascript code from an application that uses a .NET WebBrowser, which is basically an embedded Internet Explorer. This service requires one of the fields to be a "file".

那么，是否有任何方法可以在表单中设置文件输入的值，因为我有内容文件，例如在一个字节数组中（而不是文件的路径;我不是试图从用户那里窃取文件:)）。

So either, is there any way to set the value of a "file" input in a form, given that I have the content of the file, such as in an array of bytes (and not the path of the file; I'm not trying to steal files from users here :) ).

或许是一种明确创建和发送POST请求而不是动态创建FORM的方法？

Or perhaps a way to explicitly create and send the POST request instead of creating a FORM dynamically?

I需要使用将在我的 WebBrowser （想想IE）中运行的JavaScript代码。这可能吗？

I need to use JavaScript code that will be run in my WebBrowser (think IE). Is this possible?

推荐答案

不幸的是，这是不可能的，因为它会是一个安全问题。对文件输入字段的Javascript控制非常有限。否则，人们可以使用它来窃取用户计算机上的文件。

Unfortunately this is not possible as it would be a security issue. Javascript control over file input fields is very limited. Otherwise people could use this to steal files from user's computers.

由于你可以控制浏览器，你可以使用正常的HTTPWebRequest发送文件，但它不能用JavaScript完成。

Since you have control over the browser, you can send the file using a normal HTTPWebRequest, but it can't be done in JavaScript.

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