CocoRoboDesktop/pdf1.js/node_modules/one-time/index.js

'use strict';

/**
 * Wrap callbacks to prevent double execution.
 *
 * @param {Function} fn Function that should only be called once.
 * @returns {Function} A wrapped callback which prevents execution.
 * @api public
 */
module.exports = function one(fn) {
  var called = 0
    , value;

  /**
   * The function that prevents double execution.
   *
   * @api private
   */
  function onetime() {
    if (called) return value;

    called = 1;
    value = fn.apply(this, arguments);
    fn = null;

    return value;
  }

  //
  // To make debugging more easy we want to use the name of the supplied
  // function. So when you look at the functions that are assigned to event
  // listeners you don't see a load of `onetime` functions but actually the
  // names of the functions that this module will call.
  //
  onetime.displayName = fn.displayName || fn.name || onetime.displayName || onetime.name;
  return onetime;
};