Question

我最近开始使用Object.create和类似的ES5来玩（和工作）。我不太了解Object属性的writeable属性的工作方式。规范说，默认情况下设置为false，但是如何在不使用getter和setter的情况下更改它？

或者：为什么这段代码可以正常工作：

编辑：此代码是垃圾！我还没有得到getter和setter如何在这里工作！

var ob = Object.create(Object.prototype, {
    a: { 
        value: 'not save'
     },
     b: {
        value: 'value configured, but writeable',
        writeable: true
    },
    c: {
        configurable: false,
        get: function() {
            return c;
        },
        set: function(string) {
            c = string;
        }
    }
});

ob.c = 'set d the first time'; //not doing this would give us an error in the console.log line (access to ob.c)

console.log(ob.a, ob.b, ob.c); //->not save value configured, but writeable set d the first time
ob.a = 'new a';
ob.b = 'new b';
ob.c = 'new c';

console.log(ob.a, ob.b, ob.c, ob.d); //->not save value configured, but writeable new c

为什么只有ob.c实际上是可写的，而不是ob.b - 或者我做错了什么？

编辑：此处更好的代码

var ob = Object.create(Object.prototype, {
    a: { 
        value: 'not save',

     },
     b: {
        value: 'value configured, but writeable',
        writeable: true
    },
    c: {
        configurable: false,
        get: function() {
            return this.a; // works, but is not useful because of the naming and a is not writeable
        },
        set: function(string) {
            this.a = string; // works, but is not useful because of the naming and a is not writeable
        }
    }
});

Answer 1

你有一个错字。该标准将属性定义为writable，而不是writeable。修复b定义中的拼写，它完美无缺：

 b: {
    value: 'value configured, but writeable',
    writable: true
}

JS：理解可写为Object属性

1 个答案: