promise-worker-transferable/dist/promise-worker.register.js

Communicate with a Web Worker using Promises, allowing transferList

(function(f){if(typeof exports==="object"&&typeof module!=="undefined"){module.exports=f()}else if(typeof define==="function"&&define.amd){define([],f)}else{var g;if(typeof window!=="undefined"){g=window}else if(typeof global!=="undefined"){g=global}else if(typeof self!=="undefined"){g=self}else{g=this}g.registerPromiseWorker = f()}})(function(){var define,module,exports;return (function e(t,n,r){function s(o,u){if(!n[o]){if(!t[o]){var a=typeof require=="function"&&require;if(!u&&a)return a(o,!0);if(i)return i(o,!0);var f=new Error("Cannot find module '"+o+"'");throw f.code="MODULE_NOT_FOUND",f}var l=n[o]={exports:{}};t[o][0].call(l.exports,function(e){var n=t[o][1][e];return s(n?n:e)},l,l.exports,e,t,n,r)}return n[o].exports}var i=typeof require=="function"&&require;for(var o=0;o<r.length;o++)s(r[o]);return s})({1:[function(require,module,exports){
module.exports = isPromise;

function isPromise(obj) {
  return !!obj && (typeof obj === 'object' || typeof obj === 'function') && typeof obj.then === 'function';
}

},{}],2:[function(require,module,exports){
'use strict';

var isPromise = require(1);

function registerPromiseWorker(callback) {

  function postOutgoingMessage(e, messageId, error, result) {
    function postMessage(msg, transferList) {
      /* istanbul ignore if */
      if (typeof self.postMessage !== 'function') { // service worker
        e.ports[0].postMessage(msg, transferList);
      } else { // web worker
        self.postMessage(msg, transferList);
      }
    }
    if (error) {
      /* istanbul ignore else */
      if (typeof console !== 'undefined' && 'error' in console) {
        // This is to make errors easier to debug. I think it's important
        // enough to just leave here without giving the user an option
        // to silence it.
        console.error('Worker caught an error:', error);
      }
      postMessage([messageId, {
        message: error.message
      }]);
    } else {
      if (result instanceof MessageWithTransferList) {
        postMessage([messageId, null, result.message], result.transferList);
      } else {
        postMessage([messageId, null, result]);
      }
    }
  }

  function tryCatchFunc(callback, message) {
    try {
      return {res: callback(message, withTransferList)};
    } catch (e) {
      return {err: e};
    }
  }

  function withTransferList(resMessage, transferList) {
    return new MessageWithTransferList(resMessage, transferList);
  } 

  function handleIncomingMessage(e, callback, messageId, message) {

    var result = tryCatchFunc(callback, message);

    if (result.err) {
      postOutgoingMessage(e, messageId, result.err);
    } else if (!isPromise(result.res)) {
        postOutgoingMessage(e, messageId, null, result.res);
    } else {
      result.res.then(function (finalResult) {
        postOutgoingMessage(e, messageId, null, finalResult);
      }, function (finalError) {
        postOutgoingMessage(e, messageId, finalError);
      });
    }
  }

  function onIncomingMessage(e) {
    var payload = e.data;
    if (!Array.isArray(payload) || payload.length !== 2) {
      // message doens't match communication format; ignore
      return;
    }
    var messageId = payload[0];
    var message = payload[1];

    if (typeof callback !== 'function') {
      postOutgoingMessage(e, messageId, new Error(
        'Please pass a function into register().'));
    } else {
      handleIncomingMessage(e, callback, messageId, message);
    }
  }

  function MessageWithTransferList(message, transferList) {
    this.message = message;
    this.transferList = transferList;
  }

  self.addEventListener('message', onIncomingMessage);
}

module.exports = registerPromiseWorker;
},{"1":1}]},{},[2])(2)
});