CODEWITHSUNDEEP
node.jspromise
Heqian Liu
Heqian Liu

Reputation: 3

How to add a short Timeout before each request-promise api call in a loop

So I am new to Promise, I want to use Promise to do multiple url call. Now it seems that the algorithm works but the problem is that the riot api has a rate limit, so I have to let the program wait for a short time after each api call. How should I add this?

var matchidList = [];
                for (var i = 0; i < pml.length; i++) {
                  matchidList.push(pml[i]["gameId"]);
                }

                var matchuri = "https://na1.api.riotgames.com/lol/match/v3/matches/";
                var uris = [];
                for (var i = 0; i < matchidList.length; i++) {
                  uris.push(matchuri + matchidList[i] + "?" + apikey);
                }

                Promise.map(uris, function(url) {
                  return rp.getAsync(url).spread(function(response,body) {
                          return JSON.parse(body);
                  });
                }).then(function(results) {
                     // results is an array of all the parsed bodies in order
                     console.log(results);
                     tag.checkTags("").then((tags) =>{
                       res.render('index', { result: body,
                                             val: search,
                                             matches: ''
                                           });
                     });
                }).catch(function(err) {
                    console.log(err);
                     // handle error here
                });

Upvotes: 0

Views: 977

Answers (2)

Mulan
Mulan

Reputation: 135287

Without Bluebird

Those without bluebird and still looking for Promise.delay can implement it a simple delayed Promise with ease

Promise.delay = (ms, x) =>
  new Promise(r => setTimeout(r, ms, x))
  
const logp = p =>
  p.then(console.log, console.error)
  
logp(Promise.delay(3000, 'a'))
logp(Promise.delay(2000, 'b'))
logp(Promise.delay(1000, 'c'))

// c
// b
// a

Upvotes: 2

jfriend00
jfriend00

Reputation: 707526

Since it looks like you're using Bluebird, you can use Promise.map()s concurrency setting and you can use Promise.delay():

Promise.map(uris, function(url) {
    return rp.getAsync(url).spread(function(response,body) {
        return Promise.delay(200, JSON.parse(body));
    });
}, {concurrency: 1}).then(...);

The concurrent setting will make Promise.map() only run one request at a time and Promise.delay() will chain a delayed promise to the rp.getAsync() so that Promise.map() won't go to the next iteration until the delay is done.

Upvotes: 1

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