Today I Learned

Add event listener on page resize

There is a special event listener in javascript that is called whenever a page resize is detected. The event listener is named 'resize' and can be used in the following way:

function onFrameResize(){
      Height: window.innerHeight,
      Width: window.innerWidth  

window.addEventListener("resize", onFrameResize);

"window.innerHeight" and "window.innerWidth" are functions to access the width and the height of the frame.

This functionality will come in handy when working with responsive components.

Call function when image is loaded in VueJS using @load.

In VueJS, there is a way to find out when an image is fully loaded on a web page (when the image request is finished). We achieve this using the @load event that is available in VueJS and works in the following way:


export default {
  data: {
    isImageLoaded: false,

  methods: {
    onImageLoad() {
      this.isImageLoaded = true
      // optional
      // console.log('Image is loaded')

This feature will come in handy if we want to render skeleton components while images are loading or if we want to implement lazy loading functionality.

How to use Makefiles to boost command-line productivity

Makefiles are an awesome tool which can help you become more productive command-line wise by encapsulating long commands and/or sequences of commands. They also help abstract away complexity.

One practical example of creating a make command would be setting up a Laravel project. All you need to do is create a file called Makefile and type in the following.

.PHONY setup
setup: # Setup project
    composer install
    php artisan migrate:fresh --seed
    npm install

Now, a new developer who needs to setup his/her project can skip writing down that series of commands by simply typing in the following:

make setup

But this doesn't end here. You can create virtually any command to help you automate certain processes such as creating or deleting files, changing permissions etc.

How to use factories to create relationships which follow a sequence

Factories an extremely useful tool for testing. The more complex the use case, the more awesome you find out Laravel factories are.

For instance, we might need to create a few items, each one with a different measurement of its own:

    ->has(Measurement::factory()->state(new Sequence(
        ['length' => 50, "width" => 110],
        ['length' => 65, "width" => 200],
        ['length' => 190, "width" => 295],

This will result in 3 items, each item having one unique measurement assigned. The first item will have a measurement with values corresponding to the first array in the sequence and so on.

JavaScript reduce function performance enhancement

Time complexity of implemented algorithms is an aspect which for sure should be taken into consideration when working on websites with big amounts of data. In this manner, let us test out the performance of the mother and father of all JavaScripts higher order functions - Array.prototype.reduce.

Problem description: Our API provides us with an array of objects that looks something like:

const objects = [
   { id: 1, name: "name 1"},
   { id: 2, name: "name 2"},
   { id: 3, name: "name 3"},

and we want to create a lookup table out of it, like this:

   1: "name 1",
   2: "name 2",
   3: "name 3",

using reduce:

const lookup = objects.reduce((lookup, object) => ({
     [object.id]: object.name
}), {})

It works, but the time complexity of this algorithm is (unexpectedly) O(n^3), because of the internal calls of Object.assign() that needs to copy bigger and bigger objects from iteration to iteration.

This is what JavaScript does internally:

objects.reduce((lookup, object) => Object.assign(
            Object.assign(lookup, {}), 
            { [object.id]: object.name }

Time taken:

    100 records: ~0.08ms
  1.000 records: ~1.45ms
 10.000 records: ~  18ms
100.000 records: ~2600ms
1 mill  records: ~breaks

Performance boost:

const lookup = objects.reduce((lookup, object) => {
    lookup[object.id] = object.name
    return lookup
}, {})

Time taken:

    100 records: ~0.045ms
  1.000 records: ~ 0.15ms
 10.000 records: ~  1.5ms
100.000 records: ~  3.2ms
1 mill  records: ~   20ms

Great performance improvement by avoiding Object.assign calls and new object creation in each iteration.

TypeScripts Writable Computed Refs

Writable Computed Refs can be of real help when using Vue's Composition API along with TypeScript. Let's see what they are and how we can use them by getting through an example.

Problem description: let's assume we have to display a dialog with all our online users, if there are any. At the same time, we have the option to disable dialogs on our website, for some reason. In order achieve our goals, we are using an UI library like PrimeVue, Ant or Vuetify. These assist us with a reusable Dialog component that is visible when a boolean allows it to do so, something like this:


The problem that we encounter is that of declaring our isDialogVisible reactive variable. What are the problems you may think.

  1. It should both take into consideration if we have something to display in our list (if we have users in our store - using a getter for that) AND if we are allowed to display dialogs on our website. So it cannot be a simple reactive reference.

  2. You may think: alright, it's not really a problem, that's what computed properties are for. They are reactive and build up a value based on one or more raw variables. So this should solve the problem:

const isModalVisible = computed(() => useStore().getters.getOnlineUsers.length > 0 && areModalsAllowed.value);

Theoretically that's right, but it does not really solve our specific problem, because our dialog must also be closed in 3 scenarios (that means our isDialogVisible variable should be set to false): a. when dialogs are disabled on the website b. when we click on of the dialog's close button c. when the getter returns an empty list of users

The problem is that computed properties are not overridable. Depending on how you do it you could get one of the following warnings that cause unexpected behaviour and make the application not respond to the users commands of closing the dialog:

[Vue warn]: Computed property was assigned to but it has no setter.
[Vue warn]: Write operation failed: computed value is readonly.

Of course, it's a bad idea to empty the users list in the store and make the dialogs disabled on the website when you click on the close button, or to disable the dialogs on the website when there are no users in the store, or... you got the idea.

Here's where our Writable Computed Refs come into play and help us gracefully solve our problem:

const isDialogVisible: WritableComputedRef<boolean> = computed({
      get: (): boolean => useStore().getters.getOnlineUsers.length > 0 && areModalsAllowed.value,
      set: (newValue: boolean): void => { areModalsAllowed.value = newValue }

Explanation: We can specifically state the generic WritableComputedRef<T> type and construct our isDialogVisible boolean by providing an object with specific get and set methods to computed().
Our set method will be automatically used by the Dialog component when having to close the dialog due to the "Disable dialogs" button's click event. But when one checks for its value, our provided get method will also take the getters value into consideration.

We can understand this as surrounding(proxying) our computed property with custom get and set methods while it stays reactive.

How to dynamically render components in "vue-infinite-loading" using relative heights

When working with an infinite loading library like "vue-infinite-loading" or "vue-infinite-scroll", instead of hardcoding the amount of components to be rendered per page, we might use a technique to estimate the right number, based on the height of the browser window and the height of the component.

We need to obtain both of those heights and then divide them to obtain the number we are looking for. First, we can obtain the height of the browser window by using the following command:


After that, in order to obtain the height of the components rendered in the infinite scroll window, we may use:


"clientHeight" will return the height of the component and now, we can divide the numbers obtained to get the render number. ( Note: as a safety measure, the number we get should be larger than the obtained number, therefore we need to add a number to it to be sure it will behave as desired).

By using this technique we can change the render number in a responsive manner and can avoid unnecessary requests in order to give the user a more performant user experience.

Note: We can also dynamically adjust the render number if the window size changes, by adding a watcher and the following event listener:


Where "onResize" is the action to re-calculate the render number.

How to extend interfaces declared in external libraries in Typescript

Typescript allows us to easily extend types by using module augumentation.

Let's take a look at one quick example - extending the React Material Ui Library Theme.

All we need to do is create a file ending in .d.ts at the root of our Typescript project - in this case I'll name it material-ui.d.ts:

import {
  Theme as MuiTheme,
} from '@mui/material/styles';

declare module '@mui/material/styles' {
  export interface Theme extends MuiTheme {
    customization?: Record<string, string>;

How to fix filter: blur() performance issue in Safari

The filter: blur() property in css may come in handy in some situations, but you should know of a side effect it has in Safari (tested on version 15.1 as of this writing).

The issue is a nasty performance drop around the element on which the filter is used, making every other interaction extremely slow. And it happens in Safari only. In other browsers everything works well.

One solution I've found so far is to use transform: translate3d(0, 0, 0) along with filter on the same element, to force the browser use GPU acceleration for that particular element instead of the CPU.

filter: blur(200px);
transform: translate3d(0, 0, 0);

How to set default attribute values for Laravel models

The problem:

Given the following schema:

 Schema::create('posts', function (Blueprint $table) {

We when we create a new post:

$post = new Post(["title" => "test"]);

we might expect the 'number_of_hits' to be 0, but it is null.

The solution:

To fix this, we can easily tell Laravel what default values we want for the model attributes:

class Post extends Model
   protected $attributes = [
        'number_of_hits' => 0,