如何在 JavaScript 中使函数参数保持不变?

2022-01-23 00:00:00 constants javascript ecmascript-6

我想要做的是尽可能多地使用不可变变量，从而减少我的代码中移动部分的数量.我只想在必要时使用var"和let".

What I want to do is to use as many immutable variables as possible, thus reducing the number of moving parts in my code. I want to use "var" and "let" only when it's necessary.

这行不通:

function constParam(const a){
    alert('You want me to '+a+'!');
}

有什么想法吗?

推荐答案

函数参数在 ES6 中将保持可变绑定(如 var)，对此您无能为力.您得到的最佳解决方案可能是解构 argumentsconst 初始化中的对象:

Function parameters will stay mutable bindings (like var) in ES6, there's nothing you can do against that. Probably the best solution you get is to destructure the arguments object in a const initialisation:

function hasConstantParameters(const a, const b, const c, …) { // not possible
    …
}

function hasConstantParameters() {
    const [a, b, c, …] = arguments;
    …
}

请注意，此函数将具有不同的元数 (.length)，如果需要，您必须声明一些占位符参数.

Notice that this function will have a different arity (.length), if you need that you'll have to declare some placeholder parameters.

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