Table of Contents

Warsaw, 10 March 2018


Todo-list-app is an application that allows to manage a list of tasks to do. It performs adding, updating, deleting and toggling state of each task. It has minimalistic design and basic functionality. You can see it working here:

The app repository is available here:

App is a kind of model showing how to implement MVC approach in JavaScript. Model, Controller, View (MVC) methodology separates data logic (model) from display functionality (View) and manages them using separate entity (Controller).

The managing part of program (Controller) is responsible for: 1. listening to user actions from View, 2. calling Model to perform requested operations, 3. calling View to display results from Model

Program specification

You can find detailed description of all functions in file It was generated automatically from JavaScript files using 'documentations' script.

HTML file

  • index.htm is the only HTML file in project. It is the application entry point.

CSS files

  • index.css - defines all application CSS styles
  • base.css - defines common styles

JavaScript files

All the actions and user interactions are managed by JavaScript files.

MVC model

  • app.js creates an instance of program by initiating Model, View and Controller
  • controller.js defines all user action listeners, delivers methods that connects View interactions with Model operations
  • model.js defines data management methods
  • view.js defines data displaying methods

Additional files

  • store.js delivers sample data storage solution
  • template.js delivers template function to display list items, change button states, escape characters
  • helpers.js deliver helper functions for DOM elements - querying, wrapping, delegating events

Testing results

Two stages of testing were performed: manual testing and automatic Jasmine based testing

  1. During manual testing two bugs were found:

    • misspelling function declaration "addItem"
    • risky random ID generating for list elements without checking its past occurrence
  2. Process of automatic Jasmine testing required writing additional test to already written ones. Basing on existing testing strategy new tests where added. Newly created tests were supposed to check following cases:

    • should show entries on start-up
    • should show active entries
    • should show completed entries
    • should show the content block when todos exists
    • should highlight "All" filter by default
    • should toggle all todos to completed
    • should update the view
    • should add a new todo to the model
    • should remove an entry from the model

During test writing for styling of checkbox state another bug was found . There was impropriate ID declaration in <label> selector preventing proper element styling

Bug fixing

Following list presents bugs and the way they were corrected:

  • in controller.js



replaced with

  • in index.html


  <input class="toggle-all" type="checkbox">

replaced with

  <input class="toggle-all" id="toggle-all" type="checkbox">
  • in store.js


  for (var i = 0; i < 6; i++) {
    newId += charset.charAt(Math.floor(Math.random() * charset.length));

replaced with

  var isUnique = false;

  while (!isUnique){
    for (var i = 0; i < 6; i++) {
      newId += charset.charAt(Math.floor(Math.random() * charset.length));
    isUnique = true;
    for (var i = 0; i < todos.length; i++) {
      if (todos[i].id == newId) {
        isUnique = false;


Basing on audit analysis it can be stated that page loads fast, uses small amount of memory and displays content immediately. It is based only on html, css and vanilla javascript sources and doesn't require any media files, like images or video as well as fonts or heavy and complicated style files.

Audit was performed using Developer Tools in Chrome browser (v.64, 64-bit) on Windows 10 machine. Tested page was hosted on github pages at this following link


(The worst achieved result)

  • Transferred: 27.7 KB
  • Transfer time: 625ms
  • DOM loads: 507ms
  • Page loads in: 652ms
  • JS memory heap: 9.2 - 17.2MB

The majority of loading time is done by JS scripting - over 50%, while rendering and painting take less then 10%.

Memory required by application to start is lower then 20MB which is more then suitable for majority of devices (even older ones).

Loading testing results are available on below:

Overview Performance
Memory Scripting


During analysis basic operations on app were performed. Main conclusion is that app keeps memory, computing power and GPU load on constant level.

  1. Operation of typing in, adding and deleting of two list elements

    • scripting: 16ms
    • rendering: 70.4ms
    • memory usage: +(<2)%

Performance Memory

  1. Operation of continuously switching three basic views between All, Active, Completed

    • scripting: 12.2ms
    • rendering: 32.7ms
    • memory usage: -(<1)%

Performance Memory

  1. Operation of marking one task completed

    • scripting: 2.7ms
    • rendering: 27.6ms
    • memory usage: -(<1)%

Performance Memory

  1. Operation of clearing three completed tasks

    • scripting: 7.2ms
    • rendering: 11.3ms
    • memory usage: -(<1)%

Performance Memory

Operating fully loaded application requires minimum recourses. It shows low memory usage, short scripting and rendering times..

Competitor audit

According recommendation competitors webpage was examined too. It is much more sophisticated solution. In addition to todo-list-app it contains following functionalities:

  • subpages with instructions, contact information and development options,
  • registration,
  • synchronizing,
  • printing,
  • commercials,
  • multiple lists,
  • sorting,
  • drag and drop reordering.

As these two apps differ a lot and todolistme is far more developed solution only basic parameters comparison was analyzed. There is results of basic audit for todolistme page beneath.

Loading "todolistme"

(The worst achieved result)

  • Transferred: 1100 KB
  • Transfer time: 5340ms
  • DOM loads: 1290ms
  • Page loads in: 3360ms
  • JS memory heap: 11.4 - 74.7MB

The majority of loading time is done by JS scripting - over 60%, while rendering and sources loading, painting take less approximately 10%. Memory required by application to start is over 74MB.

Loading analysis results are available below:

Overview Performance
Memory Scripting

Competitor comparison

Application comparison looks as follows:

  todo-list-app todolistme
Transferred: 27.7 KB 1100 KB
Transfer time: 625ms 5340ms
DOM loads: 507ms 1290ms
Page loads in: 652ms 3360ms
JS memory heap: 9.2 - 17.2MB 11.4 - 74.7MB



Pros (+)

  • Ready to use and sophisticated solution
  • Plenty of useful functionalities
  • Custom design
  • Number of well optimized images for better user experience and well optimized css
  • Well supported

Cons (-)

  • Loading time
  • Memory consumption
  • Overall performance strongly influenced by internal JavaScript
  • Number of third party scripts requests before and after DOM loaded
  • Commercial that delays loading and increases data transfer
  • large number of global variables


Pros (+)

  • Ready to use or develop as a module
  • Fast loading and operating
  • Low memory consumption
  • Low data transfer
  • Based on MVC model easy to understand and develop
  • Well commented code
  • Minimalistic design

Cons (-)

  • Limited functionality
  • Still requires remote storage functionality


App todo-list-app performs very efficient comparing to competitor. There is a space for further developments with regards of keeping app small and quick. It would be optimal to use dedicated CSS and continuing using vanilla JavaScript.

To-do-app can be developed as a sole application as well as a very efficient module to be combined in a larger project. One of the key challenges is to chose appropriate storage solution, that will allow to maintain its biggest advantages:

  • simplicity
  • speed
  • low recourses demand

Github acount Christopher Nowak ©