如何使用JS fetch API上传文件？ [英] How do I upload a file with the JS fetch API?

问题描述

我仍然试图绕过它。

我可以让用户通过文件输入选择文件（甚至是多个）：

I can have the user select the file (or even multiple) with the file input:

<form>
  <div>
    <label>Select file to upload</label>
    <input type="file">
  </div>
  <button type="submit">Convert</button>
</form>

我可以使用提交事件来捕获<在此处填写您的事件处理程序> 。但是，一旦我这样做，我如何使用 fetch 发送文件？

And I can catch the submit event using <fill in your event handler here>. But once I do, how do I send the file using fetch?

fetch('/files', {
  method: 'post',
  // what goes here? What is the "body" for this? content-type header?
}).then(/* whatever */);

推荐答案

这是带注释的基本示例。您正在寻找上传功能：

This is a basic example with comments. The upload function is what you are looking for:

// Select your input type file and store it in a variable
const input = document.getElementById('fileinput');

// This will upload the file after having read it
const upload = (file) => {
  fetch('http://www.example.net', { // Your POST endpoint
    method: 'POST',
    headers: {
      "Content-Type": "You will perhaps need to define a content-type here"
    },
    body: file // This is your file object
  }).then(
    response => response.json() // if the response is a JSON object
  ).then(
    success => console.log(success) // Handle the success response object
  ).catch(
    error => console.log(error) // Handle the error response object
  );
};

// Event handler executed when a file is selected
const onSelectFile = () => upload(input.files[0]);

// Add a listener on your input
// It will be triggered when a file will be selected
input.addEventListener('change', onSelectFile, false);

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