promise-toolbox/nodeify.js

Essential utils for promises

"use strict";

const setFunctionNameAndLength = require("./_setFunctionNameAndLength");

const wrapApply = require("./wrapApply");

const slice = Array.prototype.slice;

const nodeify = fn => setFunctionNameAndLength(function () {
  const last = arguments.length - 1;
  let cb;

  if (last < 0 || typeof (cb = arguments[last]) !== "function") {
    throw new TypeError("missing callback");
  }

  const args = slice.call(arguments, 0, last);
  wrapApply(fn, args).then(value => cb(undefined, value), cb);
}, fn.name, fn.length + 1);

module.exports = nodeify;