分配给基元的值将丢失 [英] Value assigned to primitive will be lost

问题描述

如果我有一个对象数组，并循环遍历它们为每个对象分配一个属性值，WebStorm警告我：

If I have an array of objects, and loop through them assigning a value to an attribute for each one, WebStorm warns me:

分配给基元的值将丢失

Values assigned to primitive will be lost

但是，在控制台中进行测试时，我不会丢失任何值。

However, when testing in the console, I do not "lose" any values.

这只发生在循环在函数内部时。

This only happens when the loop is inside of a function.

下面这个错误的一个例子：

An example of this error below:

let people = [
    {
        name: 'Foo',
        age: 21,
        surname: 'FooBar'
    },

    {
        name: 'Bar',
        age: 51,
        surname: 'FooBar'
    }
];

没有函数包装器：

people.forEach(function (person) {
    person.surname = 'Baz'; // No error. Works in console.
});

使用函数包装器：

function changeSurname(people) {
    people.forEach(function (person) {
        person.surname = 'Baz'; // Error warning me that value assigned to primitive will be lost.
    });
}

changeSurname(people);

这两个都在控制台中产生相同的输出（姓氏改为'baz'）。

Both of these produce the same output in the console (the surname is changed to 'baz').

我认为这与对象引用和 person 指向的内容有关，但我不确定究竟是什么。

I assume this has something to do with the object reference and what person points to, but I am not sure exactly what.

为什么我会看到这个错误？

Why do I see this error?

WebStorm试图拯救我的潜在错误是什么？

What potential bug is WebStorm trying to save me from?

推荐答案

你的代码没有任何不当之处，WebStorm的类型推断有点混乱（JavaScript的这方面特别令人困惑） 。

There's nothing improper in your code, WebStorm's type inference is getting a bit confused (this aspect of JavaScript is particularly confusing).

它的linter看到一个字符串并假设你会尝试这样的事情：

Its linter sees a string and assumes you will try something like this:

var primitive = "september";
primitive.vowels = 3;

primitive.vowels;
// => undefined

哪会导致'丢失'值。

事实上它只是捕获函数内部的'错误'似乎是一个应该报告的彻头彻尾的错误。

The fact that it only catches this 'error' inside of a function seems like an outright bug that should be reported.

为了进一步理解这个奇怪的JavaScript部分，我推荐Angus Croll的优秀深度文章这里。

To further understand this weird part of JavaScript, I recommend Angus Croll's excellent in-depth article here.

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