How to pass parameter to a promise function

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 some_function = 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:

some_module.some_function(username, password).then(function (uid) {
  // stuff
});

ES6:

const some_function = (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:

some_module.some_function(username, password).then((uid) => {
  // stuff
});