obj.x = 'foo'; // TypeError: can't define property "x": "obj" is not extensible 在严格模式和非严格模式下两种模式下,调用Object.defineProperty()向标记为不可扩展的对象添加新属性都会报 TypeError 错误。 var obj = { }; Object.preventExtensions(obj); Object.defineProperty(obj, 'x', { val...
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...
throw new TypeError('bad set'); d.set = s; } if (('get' in d || 'set' in d) && ('value' in d || 'writable' in d)) throw new TypeError('identity-confused descriptor'); return d; } if (typeof obj !== 'object' || obj === null) throw new TypeError('bad obj'); p...
Object.defineProperty(o, "a", {enumerable : true}); // throws a TypeError (set was undefined previously) Object.defineProperty(o, "a", {set : function(){}}); // throws a TypeError (even though the new get does exactly the same thing) Object.defineProperty(o, "a", {get : function...
否则报错:Uncaught TypeError: Invalid property descriptor. Cannot both specify accessors and a value or writable attribute, #<Object>at Function.defineProperty (<anonymous>) at<anonymous>:2:8第二段代码:varwaterfall={}; Object.defineProperty(waterfall,'name',{ ...
TypeError: Cannot read properties of undefined (reading 'define') at Object.<anonymous> (B:\Builds\React-Express\nakargo\server\config\models\user.models.js:4:29) at Module._compile (node:internal/modules/cjs/loader:1546:14) at Object..js (node:internal/modules/cjs/loader:1689:10) at Mod...
"use strict"; // 这样尝试修改 undefined 会抛出错误 window.undefined = "something else"; // TypeError: Cannot assign to read only property 'undefined' of object '#<Window>' 问题2:检查变量是否真的未定义 在某些情况下,需要区分 undefined 和null 或其他假值。 原因: 代码语言:txt 复制 let value...
TypeError: Cannot define property: "x", object is not extensible. (Chrome) Error type TypeError What went wrong? Usually, an object is extensible and new properties can be added to it. However, in this caseObject.preventExtensions()marked an object as no longer extensible, so that it...
});// 抛出错误 TypeError: value appears only in data descriptors, get appears only in accessor descriptors get: 当我们通过person.name访问name的值时,get将被调用。该方法可以自定义返回的具体值是多少。get默认值为undefined set: 当我们通过person.name = 'Jake'设置name的值时,set方法将被调用。该方法...
TypeError Ifois not an object, or if any of the specified properties cannot be created or configured. This function is not atomic: it may create or configure certain properties and then throw an error, before even attempting to create or configure other properties. SeeProperty Attributesfor a ...