Q.js - Using deferred

Question

How do I get the value of the text from the example below?

Q.js has an example on using Deferred:

var deferred = Q.defer();
FS.readFile(\"foo.txt\", \"ut         


        

Answer 1

deferred.promise.then(function (text) {
  console.log(text); // Bingo!
});

Answer 2

Q = require('q');
FS = require('fs');

var deferred = Q.defer();
FS.readFile("client-02.html", "utf-8", function (error, text) {
  if (error) {
    deferred.reject(new Error(error));
    } else {
    deferred.resolve(text);
    }
return deferred.promise.done( setTimeout(console.log(text),1000 ));
});

Answer 3

See https://github.com/kriskowal/q#adapting-node

Can be rewritten in a nodejs-like:

var read = Q.nfcall(FS.readFile, FS, "foo.txt", "utf-8");
read().then( function (text) { console.log(text) } );

Answer 4

You can get the value via the .then() method of a Promise:

function read() {
    // your snippet here...
}

read().then(function (text) {
    console.log(text);
});

Also, error handlers can be passed either as a 2nd argument to .then() or with the .fail() method:

read().fail(function (err) {
    console.log(err);
});

Answer 5

Q = require('q');
FS = require('fs');

function qread() {
  var deferred = Q.defer();
  FS.readFile("foo.txt", "utf-8", function (error, text) {
    if (error) {
  deferred.reject(new Error(error));
    } else {
  deferred.resolve(text);
    }
  });
  return deferred.promise;
};   

var foo = qread();

setTimeout(function() {
  console.log(""+foo);
},1000);

It's strange you cannot see the output for console.log(foo). Dont' know why.

Check more examples here https://github.com/kriskowal/q/wiki/Examples-Gallery