我有这个问题:我想在一个 for 循环中进行多次 fetch 调用.调用次数取决于用户输入(在我的示例中,我有三个).我怎样才能让它遍历所有的 fetch 请求,然后 console.log 关闭电话号码?
i have this problem: i want to make multiple fetch calls within a for-loop. The number of calls depend on the user input (in my example i have three). How can i make it loop through all the fetch requests and then console.log the number off calls?
函数 getPosts(){
function getPosts(){
let url = ["https://www.freecodecamp.org", "https://www.test.de/, http://www.test2.com"];
let array = new Array;
for (let i = 0; i < url.length; i++) {
console.log(url[i]);
fetch(url[i])
.then(res => {return res.text(); })
.then(res => {
let reg = /<meta name="description" content="(.+?)"/;
res = res.match(reg);
array.push(res);
console.log(res);
}
)
.catch(status, err => {return console.log(status, err);})
}
console.log (array.length);
}
它 console.logs 是 0 而不是 3,因为它不会等待所有的 Promise 都被解决.我怎样才能使它成为console.log 3?如果您知道解决方案,请帮助我.
It console.logs 0 instead of 3, cause it doesn't wait for all the promises to be resolved. How can i make it to console.log 3? If you know a solution, please help me out.
你不能调用console.log(array.length),直到之后所有的promise都完成了.那么为什么不这样呢?
You can't call console.log(array.length) until after the promises are all done. So why not something like this?
let url = ["https://www.freecodecamp.org", "https://www.test.de/, http://www.test2.com"];
let array = new Array;
var fetches = [];
for (let i = 0; i < url.length; i++) {
console.log(url[i]);
fetches.push(
fetch(url[i])
.then(res => {return res.text(); })
.then(res => {
let reg = /<meta name="description" content="(.+?)"/;
res = res.match(reg);
array.push(res);
console.log(res);
}
)
.catch(status, err => {return console.log(status, err);})
);
}
Promise.all(fetches).then(function() {
console.log (array.length);
});
}
Promise.all 等待所有提取完成,然后它会打印 #.
Promise.all waits for all the fetches to finish, THEN it'll print the #.
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