CODEWITHSUNDEEP
javascriptpromise
Martin AJ
Martin AJ

Reputation: 6697

How can I call a function with promise?

Here is my code:

var gblink = require('./getbloglinks');

new Promise(function (resolve, reject) {
     var getLinks = gblink.getBlogLinks("www.example.com");
     resolve(getLinks);

}).then(function (data) {
     console.log("here");
     console.log(data);
     return false;
})

gblink.getBlogLinks() is a function which gets a URL and returns all links in that page (after a short time). When I run my code, immediately console.log("here"); will be printed and then console.log(data); will be printed as undefined.

Anyway how can I make that promise waiting until the result of getBlogLinks() returns?

Noted that when I call gblink.getBlogLinks() function manually, it works as well, it just takes a while and all I need to do now is implementing a waiting system for that function.

Here is gblink.getBlogLinks():

const NN = require('nightmare');

exports.getBlogLinks = function (data){

    const n = NN({show:true});

    n.goto(data)

    .evaluate(() => {

        var data = document.querySelectorAll("a[target='_blank']");

        arr = [];
        i=0;
        Array.from(data).forEach( function(x){
            arr[i] = x.href;
            i++;
        });
        return arr;
    })
    .then((data) => {
        return n.end(data);


    })
}

Upvotes: 0

Views: 55

Answers (2)

Sandeep Gupta
Sandeep Gupta

Reputation: 7250

getBlogLinks is not returning the promise. Doing that should solve the problem.

const NN = require('nightmare');

exports.getBlogLinks = function (data){

    const n = NN({show:true});

    return n.goto(data)

        .evaluate(() => {

            var data = document.querySelectorAll("a[target='_blank']");

            arr = [];
            i=0;
            Array.from(data).forEach( function(x){
                arr[i] = x.href;
                i++;
            });
            return arr;
        })
        .then((data) => {
            n.end(data);
            return data;
        })
};

Edited:

var gblink = require('./getbloglinks');

new Promise(function (resolve, reject) {
     var getLinks = gblink.getBlogLinks("www.example.com");
     console.log(getLinks);//========= Here You will get Pending promise =========
     resolve(getLinks);

}).then(function (data) {
     console.log("here");
     console.log(data);//========= Here You will get the array=========
     return false;
})

Edited2:

var gblink = require('./getbloglinks');

/*
new Promise(function (resolve, reject) {
    var getLinks = gblink.getBlogLinks("www.example.com");
    console.log(getLinks);//========= Here You will get Pending promise =========
    resolve(getLinks);

})*/
//Below is recommended way to chain the promise, avoid promise constructor, if not needed
gblink.getBlogLinks("www.example.com")
    .then(function (data) {
        console.log("here");
        console.log(data);//========= Here You will get the array=========
        return false;
    })

Upvotes: 2

Aseem Upadhyay
Aseem Upadhyay

Reputation: 4537

I am assuming that getBlogLinks() is a function implemented in your scope of development.

So, what is happening, in your current code of getBlogLInks() the response is getting returned only when there is a response. But the way you call it, it's synchronous.

Your getBlogLinks need to be wrapped in a promise.

getBlogLinks(data) {
  return new Promise( function(resolve,reject) {
      ....all your function code
      .then(data) {
          resolve(data); 
       }
  });
  }

then use getBlogLinks().then and you will have your answer

Upvotes: 0

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