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• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

Symbol.toStringTag well-known symbol is a string valued property that is used in the creation of the default string description of an object. It is accessed internally by the Object.prototype.toString() 方法。

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

特性属性在 Symbol.toStringTag
可写	no
可枚举	no
可配置	no

范例

Default tags

Object.prototype.toString.call('foo');     // "[object String]"
Object.prototype.toString.call([1, 2]);    // "[object Array]"
Object.prototype.toString.call(3);         // "[object Number]"
Object.prototype.toString.call(true);      // "[object Boolean]"
Object.prototype.toString.call(undefined); // "[object Undefined]"
Object.prototype.toString.call(null);      // "[object Null]"
// ... and more
				

Built-in toStringTag symbols

Object.prototype.toString.call(new Map());       // "[object Map]"
Object.prototype.toString.call(function* () {}); // "[object GeneratorFunction]"
Object.prototype.toString.call(Promise.resolve()); // "[object Promise]"
// ... and more
				

Custom classes default to object tag

When creating your own class, JavaScript defaults to the "Object" tag:

class ValidatorClass {}
Object.prototype.toString.call(new ValidatorClass()); // "[object Object]"
				

Custom tag with toStringTag

Now, with the help of toStringTag , you are able to set your own custom tag:

class ValidatorClass {
  get [Symbol.toStringTag]() {
    return 'Validator';
  }
}
Object.prototype.toString.call(new ValidatorClass()); // "[object Validator]"
				

toStringTag available on all DOM prototype objects

Due to a WebIDL spec change in mid-2020, browsers are adding a Symbol.toStringTag property to all DOM prototype objects. For example, to acccess the Symbol.toStringTag property on HTMLButtonElement :

let test = document.createElement('button');
test.toString(); // Returns [object HTMLButtonElement]
test[Symbol.toStringTag];  // Returns HTMLButtonElement
				

规范

规范
ECMAScript (ECMA-262) The definition of 'Symbol.toStringTag' in that specification.

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

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
toStringTag	Chrome 49	Edge 15	Firefox 51	IE No	Opera 36	Safari 10	WebView Android 49	Chrome Android 49	Firefox Android 51	Opera Android 36	Safari iOS 10	Samsung Internet Android 5.0	nodejs 6.0.0 6.0.0 4.0.0 Disabled Disabled From version 4.0.0: this feature is behind the --harmony runtime flag.
toStringTag available on all DOM prototype objects	Chrome 50	Edge 79	Firefox 78	IE No	Opera 37	Safari 14	WebView Android 50	Chrome Android 50	Firefox Android No	Opera Android 37	Safari iOS 14	Samsung Internet Android 5.0	nodejs No

图例

完整支持

完整支持

不支持

不支持

用户必须明确启用此特征。

用户必须明确启用此特征。

另请参阅

• Object.prototype.toString()

元数据

• 最后修改： Jun 14, 2020

相关话题

1. 标准内置对象
2. Symbol
3. 特性
   1. Symbol.asyncIterator
   2. Symbol.hasInstance
   3. Symbol.isConcatSpreadable
   4. Symbol.iterator
   5. Symbol.match
   6. Symbol.matchAll
   7. Symbol.prototype.description
   8. Symbol.replace
   9. Symbol.search
   10. Symbol.species
   11. Symbol.split
   12. Symbol.toPrimitive
   13. Symbol.toStringTag
   14. Symbol.unscopables
4. 方法
   1. Symbol.for()
   2. Symbol.keyFor()
   3. Symbol.prototype.toSource()
   4. Symbol.prototype.toString()
   5. Symbol.prototype.valueOf()
   6. Symbol.prototype[@@toPrimitive]
5. 继承：
6. Function
7. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
8. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
9. Object
10. 特性
    1. Object.prototype.__proto__
    2. Object.prototype.constructor
11. 方法
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toSource()
    10. Object.prototype.toString()
    11. Object.prototype.valueOf()
    12. Object.setPrototypeOf()