React除了不建议props对象作为可修改对象外,还不建议把传给style属性的对象作为可修改对象。并且从React 16开始也把冻结了(Object.freeze): if (propKey === STYLE) { if (__DEV__) { if (nextProp) { // Freeze the next style object so that we can assume it won't be // mutated. We have a...
The JavaScript exception "can't define property "x": "obj" is not extensible" occurs whenObject.preventExtensions()marked an object as no longer extensible, so that it will never have properties beyond the ones it had at the time it was marked as non-extensible. Message TypeError: Cannot ad...
当方法 Object.preventExtensions(obj) 被调用时,你会得到错误。 'use strict'; var obj = {}; Object.preventExtensions(obj); obj.x = 'foo'; 你会得到错误 Uncaught TypeError: Cannot add property x, object is not extensible 原文由 randominstanceOfLivingThing 发布,翻译遵循 CC BY-SA 3.0 许可协议...
TypeError:can't define property"x":"obj"is notextensible(Firefox)TypeError:Cannot define property:"x",object is not extensible.(Chrome) 错误类型 TypeError 哪里错了? 通常,一个对象是可扩展的,新的属性可以被添加到它。但是,在这种情况下,Object.preventExtensions()标记为不再可扩展的对象,因此它永远不会...
【1】Object.getOwnPropertyDescriptor() Object.getOwnPropertyDescriptor(o,name)方法用于查询一个属性的描述符,并以对象的形式返回 查询obj.a属性时,可配置性、可枚举性、可写性都是默认的true,而value是a的属性值1 查询obj.b属性时,因为obj.b属性不存在,该方法返回undefined ...
"use strict";var obj = {};Object.preventExtensions(obj);obj.name = "Frankie"; // 报错，Uncaught TypeError: Cannot add property name, object is not extensible 严格模式下，删除一个不可删除的属性，会报错。"use strict";// 报错，Uncaught TypeError: Cannot delete property 'prototype' of function...
Object.prototype.propertyIsEnumerable() 实例对象的propertyIsEnumerable方法返回一个布尔值,用来判断某个属性是否可遍历。 var obj = {}; obj.p = 123; obj.propertyIsEnumerable('p') // true obj.propertyIsEnumerable('toString') // false 元属性 ...
VM210:3 Uncaught TypeError: Cannot add property 5, object is not extensible 3. Object.seal() Object.seal() 顾名思义就是密封对象,它是另一种使对象不可变的方法。相对于freeze(),Object.seal() 方法仅保护对象不能添加和删除属性,它允许更新现有的属性。
这 Object.seal()函数 可防止在 JavaScript 对象上添加、删除或重新配置属性。const sealed = Object.seal({ answer: 42 });sealed.answer = 43; // OK// TypeError: Cannot delete property 'answer' of #<Object>delete sealed.answer;// TypeError: Cannot add property newProp, object is not extensibl...
constgame =Object.freeze({name:'Warcraft'});game.developer ='Blizzard';//TypeError: Cannot add property developer, object is not extensible 唯一需要注意的是 Object.freeze() 只冻结对象的直接属性,执行所谓的“浅冻结”。稍后我们将使用递归和其他对象...