javascript - 它工作不正常，输出未定义？

Question

这个问题已经有答案了:

Chrome/Firefox console.log always appends a line saying 'undefined' (9 个回答)

已关闭 7 年前。

function Rabbit(adjective) {
    this.adjective = adjective;
    this.describeMyself = function() {
        console.log("I am a " + this.adjective + " rabbit");
    };
}

// now we can easily make all of our rabbits
rabbit1 = new Rabbit("fluffy");
rabbit2 = new Rabbit("happy");
rabbit3 = new Rabbit("sleepy");

console.log(rabbit1.describeMyself());
console.log(rabbit2.describeMyself());
console.log(rabbit3.describeMyself());

输出:

I am a fluffy rabbit
undefined
I am a happy rabbit
undefined
I am a sleepy rabbit
undefined

如果我将其作为 .js 文件而不是控制台执行，它会停止未定义吗？或者会是一样的吗？

Answer 1

您正在尝试 console.log 一个不会返回任何内容的函数，因此结果显示为未定义。您只需调用该函数，因为其中已经有 console.log .. 试试这个

rabbit1.describeMyself();rabbit2.describeMyself();rabbit3.describeMyself();