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• 句法
• 描述
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

Object.isFrozen() determines if an object is frozen .

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.

句法

Object.isFrozen(obj)
					

参数

obj

The object which should be checked.

返回值

A 布尔 indicating whether or not the given object is frozen.

描述

An object is frozen if and only if it is not extensible , all its properties are non-configurable, and all its data properties (that is, properties which are not accessor properties with getter or setter components) are non-writable.

范例

Using Object.isFrozen

// A new object is extensible, so it is not frozen.
Object.isFrozen({}); // === false
// An empty object which is not extensible
// is vacuously frozen.
var vacuouslyFrozen = Object.preventExtensions({});
Object.isFrozen(vacuouslyFrozen); // === true
// A new object with one property is also extensible,
// ergo not frozen.
var oneProp = { p: 42 };
Object.isFrozen(oneProp); // === false
// Preventing extensions to the object still doesn't
// make it frozen, because the property is still
// configurable (and writable).
Object.preventExtensions(oneProp);
Object.isFrozen(oneProp); // === false
// ...but then deleting that property makes the object
// vacuously frozen.
delete oneProp.p;
Object.isFrozen(oneProp); // === true
// A non-extensible object with a non-writable
// but still configurable property is not frozen.
var nonWritable = { e: 'plep' };
Object.preventExtensions(nonWritable);
Object.defineProperty(nonWritable, 'e', {
  writable: false
}); // make non-writable
Object.isFrozen(nonWritable); // === false
// Changing that property to non-configurable
// then makes the object frozen.
Object.defineProperty(nonWritable, 'e', {
  configurable: false
}); // make non-configurable
Object.isFrozen(nonWritable); // === true
// A non-extensible object with a non-configurable
// but still writable property also isn't frozen.
var nonConfigurable = { release: 'the kraken!' };
Object.preventExtensions(nonConfigurable);
Object.defineProperty(nonConfigurable, 'release', {
  configurable: false
});
Object.isFrozen(nonConfigurable); // === false
// Changing that property to non-writable
// then makes the object frozen.
Object.defineProperty(nonConfigurable, 'release', {
  writable: false
});
Object.isFrozen(nonConfigurable); // === true
// A non-extensible object with a configurable
// accessor property isn't frozen.
var accessor = { get food() { return 'yum'; } };
Object.preventExtensions(accessor);
Object.isFrozen(accessor); // === false
// ...but make that property non-configurable
// and it becomes frozen.
Object.defineProperty(accessor, 'food', {
  configurable: false
});
Object.isFrozen(accessor); // === true
// But the easiest way for an object to be frozen
// is if Object.freeze has been called on it.
var frozen = { 1: 81 };
Object.isFrozen(frozen); // === false
Object.freeze(frozen);
Object.isFrozen(frozen); // === true
// By definition, a frozen object is non-extensible.
Object.isExtensible(frozen); // === false
// Also by definition, a frozen object is sealed.
Object.isSealed(frozen); // === true
					

Non-object coercion

In ES5, if the argument to this method is not an object (a primitive), then it will cause a TypeError . In ES2015, a non-object argument will be treated as if it was a frozen ordinary object, simply return true .

Object.isFrozen(1);
// TypeError: 1 is not an object (ES5 code)
Object.isFrozen(1);
// true                          (ES2015 code)
					

规范

规范
ECMAScript (ECMA-262) The definition of 'Object.isFrozen' 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
isFrozen	Chrome 6	Edge 12	Firefox 4	IE 9	Opera 12	Safari 5.1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 12	Safari iOS 6	Samsung Internet Android 1.0	nodejs Yes

图例

完整支持

完整支持

另请参阅

• Object.freeze()
• Object.preventExtensions()
• Object.isExtensible()
• Object.seal()
• Object.isSealed()

元数据

• 最后修改： May 8, 2020

相关话题

1. 标准内置对象
2. Object
3. 特性
   1. Object.prototype.__proto__
   2. Object.prototype.constructor
4. 方法
   1. Object.assign()
   2. Object.create()
   3. Object.defineProperties()
   4. Object.defineProperty()
   5. Object.entries()
   6. Object.freeze()
   7. Object.fromEntries()
   8. Object.getOwnPropertyDescriptor()
   9. Object.getOwnPropertyDescriptors()
   10. Object.getOwnPropertyNames()
   11. Object.getOwnPropertySymbols()
   12. Object.getPrototypeOf()
   13. Object.is()
   14. Object.isExtensible()
   15. Object.isFrozen()
   16. Object.isSealed()
   17. Object.keys()
   18. Object.preventExtensions()
   19. Object.prototype.__defineGetter__()
   20. Object.prototype.__defineSetter__()
   21. Object.prototype.__lookupGetter__()
   22. Object.prototype.__lookupSetter__()
   23. Object.prototype.hasOwnProperty()
   24. Object.prototype.isPrototypeOf()
   25. Object.prototype.propertyIsEnumerable()
   26. Object.prototype.toLocaleString()
   27. Object.prototype.toSource()
   28. Object.prototype.toString()
   29. Object.prototype.valueOf()
   30. Object.seal()
   31. Object.setPrototypeOf()
   32. Object.values()
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()