Web Development Articles
Using PHP Class Interface
In PHP, an interface defines a contract or blueprint that any class implementing it must follow.
It specifies method signatures (the names, parameters, and visibility of methods), however does not implement the methods.
A class that implements an interface must define all of the methods declared in the interface.
Interfaces help achieve abstraction and multiple inheritance (since a class can implement multiple interfaces).
Example:
// Define an interface
interface Employee {
public function clockIn(string $message);
}
// Implement the interface in a class
class Engineer implements Employee {
public function clockIn(string $message) {
echo "Engineer Clock In: " . PHP_EOL;
}
}
// Another class implementing the same interface
class Mechanic implements Employee {
public function clockIn(string $message) {
echo "Mechanic Clock In: " . PHP_EOL;
}
}
// Usage
function processTask(Employee $employee) {
$employee->clockIn("Task has been processed!");
}
// You can swap implementations easily
$engineer = new Engineer();
$mechanic = new Mechanic();
processTask($engineer); // Clock In Engineer
processTask($mechanic); // Clock In Mechanic
What interfaces can contain:
- Method declarations (no body/implementation)
- Constants (e.g. const MAX_LIMIT = 100;)
What interfaces cannot contain:
- Properties/variables
- Constructors with implementation
- Method bodies
Example:
interface ExampleInterface {
// Allowed
public function doSomething();
// Allowed
const VERSION = "1.0";
// Not allowed: properties inside interfaces
// public $name; // This will cause an error
}
JavaScript Self-Invoked Functions (IIFEs)
What is a self-invoked function? (IIFE)
A self-invoked function, also called an Immediately Invoked Function Expression (IIFE) is a Javascript function expression that is invoked immediately after its declaration. A self-invoked function can be a valuable tool for creating isolated scopes and managing variable privacy in javascript applications.
Key aspects of IIFEs:
- IIFEs execute immediately when defined
- Allows creation of private scopes without polluting global namespace
- Return values can be assigned to variables
- Parameters can be passed to IIFEs
Basic syntax:
(function() {
// code here
})();
// OR arrow functions (ES6+)
(() => {
// code here
})();
Why are IIFEs Necessary?
Immediate Execution with Parameters
// Immediately logs provided data
(function(date, location) {
console.log(`Date: ${date.toDateString()}`);
console.log(`Location: ${location}`);
})(new Date(), 'Seattle');
// Immediately logs:
// Date: Thu Oct 16 2025
// Location: Seattle
Avoiding Global Namespace Pollution
// if multiple scripts use the same variable names
// they won't conflict
(function() {
const restaurant = "Dairy Queen";
console.log(user); // "Dairy Queen"
})();
(function() {
const restaurant = "Burger King";
console.log(user); // "Burger King"
})();
Data Privacy/Encapsulation
// Problem: counter value is vulnerable.
var counter = 0;
function increment() {
return ++counter;
}
// FIX: keeps variables private. counterModule isn't directly accessible
const counterModule = (function() {
let count = 0;
return {
increment: function() {
return ++count;
},
decrement: function() {
return --count;
},
getCount: function() {
return count;
}
};
})();
counterModule.count = 100; // WONT WORK!!
// count is not accessible directly
console.log(counterModule.getCount()); // 0
counterModule.increment();
console.log(counterModule.getCount()); // 1
// OUPTUT: 0 1
Module Pattern Implementation
const User = (function() {
let memory = 0;
function add(a, b) {
return a + b;
}
function store(value) {
memory = value;
}
function recall() {
return memory;
}
// Only expose public methods
return {
add: add,
store: store,
recall: recall
};
})();
console.log(Calculator.add(5, 3)); // 8
Calculator.store(10);
console.log(Calculator.recall()); // 10
// memory is private and inaccessible
How To Use PHP Late Static Binding
self:: vs static:: in PHP is all about inheritance and late static binding. So what is late static binding. When building a child class there may be a static property that overrides that same static property on the parent. So when extending this class you will potentially need access to the property on both classes. The way to do this is through late static binding. You can use the self:: and static:: operators to accomplish this.
self::
- Refers to the class where the method is defined.
- Does not consider inheritance overrides.
static::
- Refers to the class that is actually called at runtime.
- This is called late static binding.
- Allows child classes to override static properties/methods and still be respected.
Example: self:: vs static::
class Animal {
public static $type = "Generic Animal";
public static function getTypeUsingSelf() {
return self::$type; // bound to Animal
}
public static function getTypeUsingStatic() {
return static::$type; // late static binding
}
}
class Dog extends Animal {
public static $type = "Dog";
}
// ------------------- USAGE -------------------
echo Dog::getTypeUsingSelf(); // Output: Generic Animal
echo "<br>";
echo Dog::getTypeUsingStatic(); // Output: Dog
PHP $this, self and parent operators
Sometimes different aspects of object oriented programming can be a little confusing if you can’t picture a use case for them. Three class operators in PHP where usage can be a little confusing at times are $this, self and parent. In this article I will try to break things down and maybe you can see where you can use this in your code. Ok so let’s begin.
1. $this
- Refers to the current object instance.
- You use $this when you want to access properties or methods of the current object.
Example:
class Animal {
public $name;
public function setName($name) {
$this->name = $name; // "this object’s" name
}
public function getName() {
return $this->name; // returns "this object’s" name
}
}
$dog = new Animal();
$dog->setName("Buddy");
echo $dog->getName(); // Output: Buddy
2. self
- Refers to the current class itself, not the instance.
- Used for static methods and static properties.
- Does not depend on an object ($this is not available in static context).
Example:
class MathHelper {
public static $pi = 3.14159;
public static function circleArea($radius) {
return self::$pi * $radius * $radius; // accessing static property with self
}
}
echo MathHelper::circleArea(5); // Output: 78.53975
3. parent
- Refers to the immediate parent class.
- Used when you want to access a method or constructor from the parent class that is overridden in the child.
Example:
class Animal {
public function makeSound() {
return "Some generic animal sound";
}
}
class Dog extends Animal {
public function makeSound() {
// Call parent method, then add more
return parent::makeSound() . " and Woof!";
}
}
$dog = new Dog();
echo $dog->makeSound(); // Output: Some generic animal sound and Woof!
Now to summarize:
- $this refers to an instance of the class. It isn’t available in a static context, therefore cannot be used within a static class function.
- The self:: operator refers to the class-level property. It is used in a static context and refers to the actual class itself.
- The parent:: operator calls the overridden method from the parent class. It’s used in inheritance typically to call an overwritten method on the parent class.
Here is a really good example that should help you concieve these concepts and clear up any confusion.
class Animal {
public $name;
public static $kingdom = "Animalia";
public function __construct($name) {
$this->name = $name; // instance reference
}
public function describe() {
return "I am an animal named {$this->name}.";
}
public static function getKingdom() {
return "Kingdom: " . self::$kingdom; // static reference
}
}
class Dog extends Animal {
public function describe() {
// Use parent to get base description
$base = parent::describe();
// Add Dog-specific description
return $base . " I am also a dog that says Woof!";
}
public function introduce() {
// `$this` calls instance method
return $this->describe();
}
public static function getInfo() {
// `self` calls static property from this class (or parent if not overridden)
return "Dogs belong to " . self::$kingdom;
}
}
// ------------------- USAGE -------------------
// Create an object
$dog = new Dog("Buddy");
// $this -> instance reference
echo $dog->introduce();
// Output: I am an animal named Buddy. I am also a dog that says Woof!
echo "<br>";
// self -> static reference
echo Dog::getInfo();
// Output: Dogs belong to Animalia
echo "<br>";
// parent -> calling parent method inside child
echo $dog->describe();
// Output: I am an animal named Buddy. I am also a dog that says Woof!
echo "<br>";
// static method from parent
echo Animal::getKingdom();
// Output: Kingdom: Animalia
Solve Vue.js Component Overload with Parent-Child Patterns
Has your Vue component become a tangled mess? Too much template markup, too many responsibilities, and decreasing maintainability.
Well the solution is to use component composition with parent-child relationships that Vue provides.
In this tutorial, you'll learn to:
1. Refactor effectively breaking up monolithic components into focused children
2. Pass data gracefully using props to send data from parent to child
3. Handle child events by capturing custom events emitted by child components
4. Maintain clean data flow by establishing predictable communication between components
See a real-world example where a parent component delegates UI to a specialized Toolbar child, creating cleaner code and better separation of concerns.
Parent Component:
<template>
<div class="parent-component">
<h2>Evaluate Product</h2>
<Toolbar :message="message" @evaluate-product="evaluate" />
<div class="parent-data">
<p>Total Likes: {{ total.likes }}</p>
<p>Total Dislikes: {{ total.dislikes }}</p>
<p v-if="action">Last Action: {{ action }}</p>
</div>
</div>
</template>
<script>
import Toolbar from './Toolbar.vue';
export default {
name: 'EvaluateComponent',
components: {
Toolbar
},
data(){
return {
total: {
likes: 0,
dislikes: 0
},
message: '',
action: null,
messageTimeout: null
}
},
methods:{
evaluate(task) {
// Clear previous timeout
if (this.messageTimeout) {
clearTimeout(this.messageTimeout);
}
switch(task) {
case 'like':
this.total.likes++;
this.message = "Like incremented successfully!";
this.action = 'like';
break;
case 'dislike':
this.total.dislikes++;
this.message = "Dislike incremented successfully!";
this.action = 'dislike';
break;
}
// Auto-clear message after 3 seconds
this.messageTimeout = setTimeout(() => {
this.message = '';
}, 3000);
}
},
beforeDestroy() {
// Clean up timeout when component is destroyed
if (this.messageTimeout) {
clearTimeout(this.messageTimeout);
}
}
}
</script>
Child Component (Toolbar tag in the parent):
<template>
<div class="child-component">
<div class="message" v-if="messageSet">{{ message }}</div>
<button @click="performEvaluate('like')">Like</button>
<button @click="performEvaluate('dislike')">Dislike</button>
</div>
</template>
<script>
export default {
props: {
message: {
type: String,
default: ''
}
},
data() {
return {
// You can add data properties here if needed
}
},
emits: ['evaluate-product'],
computed: {
messageSet() {
return this.message.length > 0;
}
},
methods: {
performEvaluate(evaluation) {
this.$emit('evaluate-product', evaluation);
}
}
}
</script>
How to use JavaScript Promise catch()
There are a few ways to take advantage of the Promise catch method. The catch() method is run when the Promise is rejected or throws an error. Return value from a Promise is passed forward to the catch() method. Promises can be chained as well. It simply forwards the return value from the chained Promise to the catch method if the Promise is rejected or an error is thrown.
A basic example of using catch() with a Promise reject:
// using Promise.reject
let rejectPromise = new Promise(function(resolve, reject){
reject("promise rejected")
})
function displayCatch(x) {
console.log(x)
}
rejectPromise.catch(x => displayCatch(x))
A basic example of using catch() by throwing an error from the promise:
// throw an error
let promiseError = new Promise(function(resolve, reject){
throw "throw error"
})
function displayCatch(x) {
console.log(x)
}
promiseError.catch(x => displayCatch(x));
Chained promises. Reject or throw error from chained Promise:
let resolvePromise = new Promise(function(resolve, reject) {
setTimeout(resolve, 50, "resolved chained");
})
function resolveDisplay(x) {
console.log(x)
throw "throw error from chained Promise"
}
function displayCatch(x) {
console.log(x)
}
resolvePromise.then(x => resolveDisplay(x)).catch(x => displayCatch(x))
Mastering Promise Chaining with .then() in JavaScript
Have you ever made an HTTP API request in JavaScript, only to find the data you need is mysteriously unavailable? You're confident the server-side API works, as you've tested it repeatedly. The issue often lies in JavaScript's asynchronous nature.
JavaScript doesn't pause execution to wait for slow operations, like API calls, to complete. Instead, it triggers the request and immediately moves on to the next line of code. By the time your script tries to use the response data, the request may not have finished.
This is where the Promise object becomes essential. A Promise represents the eventual completion (or failure) of an asynchronous operation and its resulting value. Let's explore how to use them effectively.
1. Basic Promise Handling with .then()
The .then() method is the primary way to interact with a Promise. You can pass it two functions: one to handle a successful resolution and another to handle a rejection.
var name = "Mary"
const promise = new Promise((resolve, reject) => {
name == "Mary" ? resolve(name) : reject(name)
});
// promise.then(ifResolved, ifRejected)
promise.then(
x => console.log(`name resolved: ${x}`),
x => console.log(`name rejected: ${x}`)
) // expected output "name resolved: Mary"
2. Chaining Multiple .then() Methods
Promises are powerful because they can be chained, allowing you to define a sequence of asynchronous steps. Each .then() in the chain receives the result from the previous one.
var name = "Mary"
// initial method provided to the Promise
const analyzeName = (resolve, reject) => {
name == "Mary" ? resolve(name) : reject(name)
}
// method to handle resolved
const nameResolved = x => {
console.log(`Name resolved: ${x}`)
return x
}
// method to handle rejected
const nameRejected = x => {
console.log(`Name rejected: ${x}`)
return x
}
// Step 2
const step2 = x => {
console.log(`Step 2: ${x}`)
return x
}
// Step 3
const step3 = x => {
console.log(`Final Step: ${x}`)
return x
}
const namePromise = new Promise(analyzeName)
namePromise.then(
x => nameResolved(x), // Expected "Name Resolved: Mary"
x => nameRejected(x) // Expected "Name Rejected Mary"
)
.then(x => step2(x)) // Expected "Step 2: Mary"
.then(x => step3(x)) // Expected "Final Step: Mary"
// Name Resolved: Mary
// Step 2: Mary
// Final Step: Mary
Key Takeaway
By using Promises and their .then() method, you gain precise control over the flow of your asynchronous code. This ensures that each step waits for the previous one to complete before executing, which is the fundamental solution to the "missing data" problem in async operations like API calls. For modern, cleaner syntax, consider using async/await, which is built on top of Promises.