javascript 警告 ESLint 规则下的意外未命名函数 func-names
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Warning Unexpected unnamed function func-names under, ESLint rule
提问by Zapar Siddik
My eslintversion is 4.18.2, it would give a warning like this:
我的eslint版本是 4.18.2，它会给出这样的警告：
Unexpected unnamed function
Expected an assignment or function call and instead saw an expression
意外的未命名函数
预期是赋值或函数调用，而是看到了一个表达式
When defining functions in such a way:
当以这种方式定义函数时：
const farmerIds = a.reduce((function (hash) {
return function (prev, curr) {
!hash[curr.farmerId] && (hash[curr.farmerId] = prev.push(curr));
return prev;
};
}(Object.create(null))), []);
回答by Patrick Hund
These are two different issues…
这是两个不同的问题……
Unexpected unnamed function
意外的未命名函数
This is, as pointed out by Constantin, the ESLint rule func-names.
正如康斯坦丁所指出的，这就是 ESLint 规则func-names。
If you don't want to disable this rule, you can either use names for your functions, like so:
如果您不想禁用此规则，您可以为您的函数使用名称，如下所示：
const farmerIds = a.reduce((function reducer(hash) {
return function fn(prev, curr) {
!hash[curr.farmerId] && (hash[curr.farmerId] = prev.push(curr));
return prev;
};
}(Object.create(null))), []);
Or, and this I would recommend personally, use arrow functions:
或者，我个人建议使用箭头函数：
const farmerIds = a.reduce(
(hash => {
return (prev, curr) => {
!hash[curr.farmerId] && (hash[curr.farmerId] = prev.push(curr));
return prev;
};
})(Object.create(null)),
[]
);
Expected an assignment or function call and instead saw an expression
期望赋值或函数调用，而是看到了一个表达式
ESLint is complaining about this line, which is indeed an expression, not an assignment or function call:
ESLint 抱怨这一行，它确实是一个表达式，而不是赋值或函数调用：
!hash[curr.farmerId] && (hash[curr.farmerId] = prev.push(curr));
You can rewrite it as an ifstatement:
您可以将其重写为if语句：
if (!hash[curr.farmerId]) {
hash[curr.farmerId] = prev.push(curr);
}
Fixing both
修复两者
Putting the code examples above together, this code should run without ESLint complaining:
将上面的代码示例放在一起，这段代码应该可以在没有 ESLint 抱怨的情况下运行：
const farmerIds = a.reduce(
(hash => (prev, curr) => {
if (!hash[curr.farmerId]) {
hash[curr.farmerId] = prev.push(curr);
}
return prev;
})(Object.create(null)),
[]
);
Note that I've also removed the curly braces around the body of the first arrow function, which is a nice additional feature of arrows to keep the code more concise.
请注意，我还删除了第一个箭头函数主体周围的花括号，这是箭头的一个很好的附加功能，可以使代码更加简洁。
