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• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

set() 方法在 FormData interface sets a new value for an existing key inside a FormData object, or adds the key/value if it does not already exist.

差异在 set() and FormData.append is that if the specified key does already exist, set() will overwrite all existing values with the new one, whereas FormData.append will append the new value onto the end of the existing set of values.

注意 : This method is available in Web 工作者 .

句法

There are two versions of this method: a two and a three parameter version:

formData.set(name, value);
formData.set(name, value, filename);
					

参数

名称

The name of the field whose data is contained in value .

value

The field's value. This can be a USVString or Blob (including subclasses such as File ). If none of these are specified the value is converted to a string.

filename 可选

The filename reported to the server (a USVString )，当 Blob or File is passed as the second parameter. The default filename for Blob objects is "blob". The default filename for File objects is the file's filename.

注意： If you specify a Blob as the data to append to the FormData object, the filename that will be reported to the server in the "Content-Disposition" header used to vary from browser to browser.

范例

The following line creates an empty FormData 对象：

var formData = new FormData(); // Currently empty
					

You can set key/value pairs on this using FormData.set :

formData.set('username', 'Chris');
formData.set('userpic', myFileInput.files[0], 'chris.jpg');
					

If the sent value is different than String or Blob it will be automatically converted to String:

formData.set('name', 72);
formData.get('name'); // "72"
					

规范

规范	状态	注释
XMLHttpRequest The definition of 'set()' in that specification.	实时标准

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
set	Chrome 50	Edge 18	Firefox 39	IE No	Opera 37	Safari 11	WebView Android 50	Chrome Android 50	Firefox Android 39	Opera Android 37	Safari iOS 11	Samsung Internet Android 5.0

图例

完整支持

完整支持

不支持

不支持

另请参阅

• XMLHTTPRequest
• 使用 XMLHttpRequest
• 使用 FormData 对象
• <form>

元数据

• 最后修改： Sep 19, 2019

相关话题

1. FormData
2. 构造函数

   1. FormData()
3. 方法

   1. append()
   2. delete()
   3. entries()
   4. get()
   5. getAll()
   6. has()
   7. keys()
   8. set()
   9. values()
4. XMLHttpRequest 相关页面

   1. XMLHttpRequest
   2. XMLHttpRequestEventTarget
   3. XMLHttpRequestUpload