How to pass parameter to a promise function

Question

this might seem a silly question but I am a newbie in this topic. I am working on promises on node js. And I want to pass parameter to a promise function. However I could not figure it out.

someModule.someFunction.then(username, password,function(uid) {
  /*stuff */
}

and the function is something like

var someFunction = new Promise(username, password, function(resolve, reject) {
  /*stuff using username, password*/
  if ( /* everything turned out fine */ ) {
    resolve("Stuff worked!");
  } else {
    reject(Error("It broke"));
  }
});

Answer 1

Wrap your Promise inside a function or it will start to do its job right away. Plus, you can pass parameters to the function:

var someFunction = function(username, password) {
  return new Promise(function(resolve, reject) {
    /*stuff using username, password*/
    if ( /* everything turned out fine */ ) {
      resolve("Stuff worked!");
    } else {
      reject(Error("It broke"));
    }
  });
}

Then, use it:

someModule.someFunction(username, password).then(function(uid) {
  /* stuff */
})

 

ES6:

const someFunction = (username, password) => {
  return new Promise((resolve, reject) => {
    /*stuff using username, password*/

    if ( /* everything turned out fine */ ) {
      resolve("Stuff worked!");
    } else {
      reject(Error("It broke"));
    }
  });
};

Use:

someModule.someFunction(username, password).then(uid => {
  /* stuff */
});