executing a "background process" in javascript

Question

executing a "background process" in javascript

Can JavaScript execute functions in the background?

I am using the pdfmake tool to generate a PDF within an AngularJS application, but the generation process takes around 3-4 seconds and causes the UI to freeze completely.

I want to run a background task to initiate the PDF download without impacting the user interface. Is this achievable?

This is how I currently implement pdfmake (with custom factories named pdfmake and _):

'use strict';

angular.module('App')

    .service('CatalogPdfService', ['pdfmake', '_', '$q', '$filter',
        function (pdfmake, _, $q, $filter) {

            var $translate = $filter('translate');
            var listDate = new Date();

            return {
                download: download
            };

            function download(data) {

                listDate = _.first(data).publishedOn;
                console.log('initiating download process');
                var deferred = $q.defer();
                var filename = $translate('APP.EXPORT.pdf.catalog.title', {date: $filter('amDateFormat')(listDate, 'DDMMYYYY')}) + '.pdf';
                create(data).download(filename, function () {
                    console.log('download completed');
                    deferred.resolve();
                });
                return deferred.promise;
            }

            // Other code implementation remains unchanged...

        }]);

javascript angularjs pdfmake

Answer 1

Answer №1

If you're looking to generate a PDF using a Web Worker, there are some restrictions to be mindful of. Check out this reference for more information.

One approach is creating an Angular factory for running tasks on a worker thread. Here's an example:

/*
Here's an example on how to get this sack of moldering spuds to do something:

 var myWorker = new MyWorker({ fn: function() {
    this.onmessage = function(args) {
        setTimeout(function() {
            this.postMessage('Got args: ' + args.data);
        }, 20000);
    };
 } });

 myWorker.do('Test').then(function(message) {
    alert(message);
 });
 */

'use strict';

angular.module('myApp')
    .factory('MyWorker', function($q) {
        var _worker;

        var MyWorker = function(settings) {
            _init(settings);
        };

        MyWorker.prototype.do = function(args) {
            var deferred = $q.defer();

            _worker.onmessage = function(message) {
                deferred.resolve(message.data);
            };

            //Fire up the blades.
            if (args)
                _worker.postMessage(args);
            else
                _worker.postMessage();

            return deferred.promise;
        };

        MyWorker.prototype.destroy = function() {
            _worker.terminate();
        };

        function _init(settings) {
            if (settings.script)
                _worker = new Worker(settings.script);
            //Need to make this IE (10+) friendly.
            else if (settings.fn) {
                var blobUrl = window.URL.createObjectURL(new Blob(
                    ['(', settings.fn.toString(), ')()'],
                    { type: 'application/javascript' }
                ));

                _worker = new Worker(blobUrl);
            }
        };

        return MyWorker;
    });

This showcases one way it can be implemented in AngularJS, but keep in mind that adjustments may be needed based on your specific requirements.

Answer 2

If you're looking to generate a PDF using a Web Worker, there are some restrictions to be mindful of. Check out this reference for more information.

One approach is creating an Angular factory for running tasks on a worker thread. Here's an example:

/*
Here's an example on how to get this sack of moldering spuds to do something:

 var myWorker = new MyWorker({ fn: function() {
    this.onmessage = function(args) {
        setTimeout(function() {
            this.postMessage('Got args: ' + args.data);
        }, 20000);
    };
 } });

 myWorker.do('Test').then(function(message) {
    alert(message);
 });
 */

'use strict';

angular.module('myApp')
    .factory('MyWorker', function($q) {
        var _worker;

        var MyWorker = function(settings) {
            _init(settings);
        };

        MyWorker.prototype.do = function(args) {
            var deferred = $q.defer();

            _worker.onmessage = function(message) {
                deferred.resolve(message.data);
            };

            //Fire up the blades.
            if (args)
                _worker.postMessage(args);
            else
                _worker.postMessage();

            return deferred.promise;
        };

        MyWorker.prototype.destroy = function() {
            _worker.terminate();
        };

        function _init(settings) {
            if (settings.script)
                _worker = new Worker(settings.script);
            //Need to make this IE (10+) friendly.
            else if (settings.fn) {
                var blobUrl = window.URL.createObjectURL(new Blob(
                    ['(', settings.fn.toString(), ')()'],
                    { type: 'application/javascript' }
                ));

                _worker = new Worker(blobUrl);
            }
        };

        return MyWorker;
    });

This showcases one way it can be implemented in AngularJS, but keep in mind that adjustments may be needed based on your specific requirements.

executing a "background process" in javascript

Answer №1

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