Object.isFrozen()

Baseline 已广泛支持

此特性已相当成熟,可在许多设备和浏览器版本上使用。自 ⁨2015 年 7 月⁩以来,各浏览器均已提供此特性。

Object.isFrozen() 静态方法用于判断一个对象是否被 冻结

试一试

const object = {
  foo: 42,
};

console.log(Object.isFrozen(object));
// Expected output: false

Object.freeze(object);

console.log(Object.isFrozen(object));
// Expected output: true

语法

js
Object.isFrozen(obj)

参数

obj

需要检查的对象。

返回值

一个 Boolean 值,指示给定对象是否被冻结。

描述

当且仅当一个对象不可 扩展,其所有属性都是不可配置的,并且其所有数据属性(即,不是带有 getter 或 setter 组件的访问器属性)都是不可写的,该对象才被视为冻结。

示例

使用 Object.isFrozen

js
// A new object is extensible, so it is not frozen.
Object.isFrozen({}); // false

// An empty object which is not extensible
// is vacuously frozen.
const vacuouslyFrozen = Object.preventExtensions({});
Object.isFrozen(vacuouslyFrozen); // true

// A new object with one property is also extensible,
// ergo not frozen.
const 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

// 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.
const 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.
const 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.
const accessor = {
  get food() {
    return "yum";
  },
};
Object.preventExtensions(accessor);
Object.isFrozen(accessor); // false

// When we make that property non-configurable 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.
const 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

非对象参数

在 ES5 中,如果传递给此方法的参数不是对象(而是原始类型),它将导致 TypeError。在 ES2015 中,如果传递非对象参数,它将返回 true 而不会报错,因为原始类型按定义是不可变的。

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

Object.isFrozen(1);
// true                          (ES2015 code)

规范

规范
ECMAScript® 2026 语言规范
# sec-object.isfrozen

浏览器兼容性

另见