javascript - 如何对字符串数组使用 apply 方法？

Question

有人可以向我解释一下为什么我无法在字符串数组上正确使用 apply 方法吗？

function speak(line) {
     console.log(line);
}
var whiteRabbit = {type: "white", speak: speak};
speak.apply(whiteRabbit, ["Burp!","Skree","Hello"]);

输出是Burp，为什么不是整个数组？如何通过 apply 方法实现这一点？

Answer 1

来自Function#apply

The apply() method calls a function with a given this value, and arguments provided as an array (or an array-like object).

您仅将数组的第一个元素作为参数line。如果您采用更多参数，您也可以看到数组的其余部分。

function speak(line, line1, line2) {
    console.log(line);
    console.log(line1);
    console.log(line2);
}

var whiteRabbit = {
    type: "white",
    speak: speak
};

speak.apply(whiteRabbit, ["Burp!", "Skree", "Hello"]);

如果您想将值用作数组，则可以使用 arguments并迭代值。

function speak() {
    Array.prototype.forEach.call(arguments, function (s) {
        console.log(s);
    });
}

var whiteRabbit = {
    type: "white",
    speak: speak
};

speak.apply(whiteRabbit, ["Burp!", "Skree", "Hello"]);

对于 ES6，你可以使用 rest parameters ...

function speak(...args) {
    args.forEach(s => console.log(s));
}

var whiteRabbit = {
    type: "white",
    speak: speak
};

speak.apply(whiteRabbit, ["Burp!", "Skree", "Hello"]);