Question

我正在尝试在Javascript中创建自定义构造函数，但我似乎无法理解为什么控制台不会记录“调查”的'字母'属性由构造函数“Verb”：

创建

function Verb (tense, transitivity) {
    this.tense = tense;
    this.transitivity = transitivity;
    **this.letter1 = this.charAt(0);
    this.letter2 = this.charAt(2);
    this.letter3 = this.charAt(4);
    this.Letters = this.letter1 + " " + this.letter2 + " " + this.letter3;**

}

var Investigating = new Verb ("present", "transitive");


console.log(Investigating.tense);  // present
**console.log(Investigating.Letters); //console doesn't log anything**

我在这里做错了什么？非常感谢你们的帮助，谢谢。

Answer 1

在构造函数内部函数this指的是正在创建的obj。所以this.charAt(0)是不正确的。因为对象对象在其原型链中没有charAt方法。（字符串和数组具有此方法）。我认为你是在尝试做。

this.letter1 = this.transitivity.charAt(0);
this.letter2 = this.transitivity.charAt(2);
this.letter3 = this.transitivity.charAt(4);
this.Letters = this.letter1 + " " + this.letter2 + " " + this.letter3;`

属性在我的自定义构造函数中无法正常运行 - Javascript

1 个答案: