限制对外部 api 节点的调用

Question

I'm, in node and I have an array of obj {suggestion: 'text', rank: '2'} that I want to use to make a call to bing to get the first result on each of them.

At the moment, I have managed it using a Promise.all

 await Promise.all(suggestions.map(async (s, i) => await bingWebSearch(s.suggestion.replace(/\s/g, '+'), i))).then(r => { suggestions.map((s, i) => console.log(` n${i+1}. ${s.suggestion} | times suggested: ${s.rank} | url: ${s.webpage} `)) }).catch(e => e.message)

that will call the function bingWebSearch and assign the website URL to the obj

 const bingWebSearch = async (query, i) => { return await axios.get('https://api.bing.microsoft.com/v7.0/search?', { headers: { 'Ocp-Apim-Subscription-Key': SUBSCRIPTION_KEY }, params: { count: 1, mkt: 'en-US', q: query } }).then(r => { if (r.data.webPages) return suggestions[i].webpage = r.data.webPages.value[0].url }).catch(e => console.log(e.message)) }

So basically, this will fire 30 calls to bing, but I am allowed only to do 3/second how I can I achieve it? I have tried with a setTimeOut, but using the async func is a bit tricky, so it did not work.

Answer 1

here is my suggestion:

 function delay(ms) { return new Promise(function (resolve) { setTimeout(resolve, ms); }); } const bingWebSearch = (query, ms) => { return new Promise((resolve, reject) => { delay(ms).then(() => { axios.get("https://api.bing.microsoft.com/v7.0/search?", { headers: { "Ocp-Apim-Subscription-Key": SUBSCRIPTION_KEY }, params: { count: 1, mkt: "en-US", q: query } }).then(r => { resolve(r.data.webPages.value[0].url); }).catch(e => { console.log(e.message); // this will just return an empty string as a result, if something goes wrong resolve(""); // you can also reject and handle the exception inside calling for loop // if more advanced error handling is required // reject(e); }); }); }); }; async function load() { const requests = suggestions.map((s, i) => { // delay each request by 400ms to avoid hitting the limit of 3 requests per second const ms = i * 400; return bingWebSearch(s.suggestion.replace(/\s/g, "+"), ms); }); const res = await Promise.all(requests); suggestions.forEach((s, i) => { s.webpage = res[i]; console.log(`n${i + 1}. ${s.suggestion} | times suggested: ${s.rank} | url: ${s.webpage}`); }); } (function () { load(); })();

I refactored bingWebSearch a bit, to only return the result, and not directly changing the list of suggestions. Try keeping functions as self contained as possible without external dependencies.