英文:
Data variable from API fetch function not working when declared
问题
我真的对js很陌生，但我已经不得不使用API并使用async/await来工作，所以我知道可能有些地方我不太明白...
这是我的代码：
async function collectWorks() {
const response = await fetch("http://localhost:5876/api/works");
const worksData = await response.json();
return worksData
}
async function testfunction() {
const worksData = await collectWorks();
let test = worksData[1].title;
console.log(test)
}
testfunction()
这是我的问题：我有一个用于获取API的异步函数。我应该在const worksData中获取数据，对吗？但当我尝试在testfunction中使用它时，它不起作用，我在控制台中得到以下错误：
Uncaught (in promise) ReferenceError: worksData is not defined at testfunction
然而，这就是我不理解的地方，当我去掉const前面的时候，它就可以正常工作，我确实得到了我需要的结果...我错过了什么？我不应该声明它吗？
（实际上，我之前注意到这一点，因为起初我忘记了添加const，然后继续进行项目，因为它运行得很好。当我注意到后，我尝试把它添加回来，但一切都崩溃了。最后我不得不重新开始，因为我认为代码的其余部分可能会对它产生影响，但现在我甚至无法开始，因为我卡在这个问题上了...我也尝试在fetch函数之前声明它。）
英文:
I'm really new to js and I already have to work with APIs and use async/await so I know there might be something I don't get here...
Here's my code:
async function collectWorks() {
const response = await fetch ("http://localhost:5876/api/works");
const worksData = await response.json();
return worksData
}
async function testfunction() {
await collectWorks();
let test = worksData[1].title;
console.log(test)
}
testfunction()
Here's my problem: I have my async function to fetch my API. I should get the data in my const worksData, correct? But when I try to use it in my testfunction it doesn't work and I get this in the console :
Uncaught (in promise) ReferenceError: worksData is not defined at testfunction
However, and that's what I don't understand, when I get rid of the const in front of worksData it works perfectly and I do get the result I need... What did I miss? Am I not supposed to declare it?
(I actually noticed this because at first I forgot to add the const and went on with my project because it worked fine. When I noticed, I tried to add it back but it broke everything. I ended up starting anew because I thought rest of the code might be messing with it but now I can't even start since I'm stuck with this problem... I've tried declaring it before the fetch function too.)
答案1
得分: 1
不要有别的内容。
你没有使用函数的返回值：
await collectWorks();
如果你希望返回值存储在一个名为 worksData（或者任何其他名字）的变量中，可以将该值存储在一个变量中：
let worksData = await collectWorks();
（就像你在 collectWorks 函数内部已经为 response 和 worksData 做的那样。）
当我去掉 worksData 前面的 const 时，它就能完美运行，我确实得到了我需要的结果
因为没有变量声明（只有赋值），它是一个 隐式全局变量。基本上它会成为 window 对象上的一个属性。一般最好避免这样做。
英文:
You're not using the return value of the function:
await collectWorks();
If you want the return value to be in a variable called worksData (or called anything at all really), store that value in a variable:
let worksData = await collectWorks();
(Exactly as you already do for response and worksData within the collectWorks function.)
> when I get rid of the const in front of worksData it works perfectly and I do get the result I need
Because without the variable declaration (only the assignment), it's an implicit global. Basically it becomes a property on the window object. Which is best to avoid in general.
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