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Dev Dastan
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🔸 Programming Tips and Concepts 👾

🔹Contact: @Hossein13M 🤘🏻
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Software Engineering Quote

💬 In software development, “perfect” is a verb, not an adjective. There is no perfect process. There is no perfect design. There are no perfect stories. You can, however, perfect your process, your design, and your stories.

🔣 Kent Beck


#Agile #softwareEngineering

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📱 JavaScript Quiz

⁉️ What is the output of this code?

function Car() {
this.make = 'Lamborghini';
return { make: 'Maserati' };
}

const myCar = new Car();
console.log(myCar.make);


✔️ Answer:
When a constructor function is invoked with the new keyword, it creates an object and sets this to refer to that object. If the constructor function doesn't explicitly return anything, it defaults to returning the newly created object. In the case of the constructor function Car, it explicitly returns a new object with 'make' set to "Maserati", overriding the default behavior. Therefore, when new Car() is called, the returned object is assigned to myCar, resulting in the output "Maserati" when myCar.make is accessed.


#JavaScript #Quiz


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📱 Promise.all vs Promise.allSettled


🕯 Promise.all and Promise.allSettled are two methods provided by JavaScript's Promise API, but they have different behaviors and use cases.

🔣 Promise.all
Waits for all promises to resolve or rejects immediately if any promise rejects. Resolves with an array of resolved values.


🔣 Promise.allSettled
Waits for all promises to settle (resolve or reject) and always resolves. Returns an array of objects representing the outcomes of the promises, including their status and value/reason.



📚 Article: [here]
📱 YouTube Video: [here]
📱 Image Credit (on X.com): [here]

#JavaScript


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🏛 API Architecture Style


🗣️ Architecture styles define how different components of an API interact with one another. As a result, they ensure efficiency, reliability, and ease of integration with other systems by providing a standard approach to designing and building APIs.

🗣️ You can check out the different types of API architecture styles in the attached image.



📚 Article: [here]
📱 YouTube Video: [here]

#systemDesign #api


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🟦 TypeScript Tips and Tricks Series (Part 1)

🔣 Template Literal Types:

Build complex string types using dynamic expressions within backticks.


type Endpoint = `/users/${number}`;

const validEndpoint: Endpoint = '/users/123';

// const invalidEndpoint: Endpoint = '/posts/456'; // Error: Type '"/posts/456"' is not assignable to type 'Endpoint'


Use Case:
representing API responses, URL patterns, or validation formats.


#TypeScript


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📱 JavaScript Quiz

⁉️ What's the value of num?

const num = parseInt('7*6', 10);


🔤 42
🔤 "42"
🔤 7
🔤 NaN

✔️ Answer:
parseInt returns only the first number in the string. Depending on the radix (the second argument specifying the number type: base 10, hexadecimal, octal, binary, etc.), parseInt validates the characters in the string. If it encounters an invalid character, it stops parsing and ignores the rest.

For example, in "78", only "7" is valid, so it parses it into the decimal 7, ignoring the "" and "8". Thus, num now equals 7.



#JavaScript #Quiz


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🖼️ React State vs Refs


🔣 State: For data that changes the UI. Updates trigger re-renders.

import { useState } from 'react';

function Counter() {
const [count, setCount] = useState(0);

return (
<div>
<p>You clicked {count} times</p>
<button onClick={() => setCount(count + 1)}>Click me</button>
</div>
);
}


🔣 Refs: For directly accessing DOM elements or storing mutable values. Don't trigger re-renders.

import { useRef } from 'react';

function InputFocus() {
const inputRef = useRef(null);

function handleFocus() {
inputRef.current.focus();
}

return (
<div>
<input ref={inputRef} />
<button onClick={handleFocus}>Focus Input</button>
</div>
);
}


Keep in mind that:

- State is immutable
- Avoid reading/writing refs during rendering
- Both persist data and have different update behaviors


📚 Article: [here]

#JavaScript #ReactJS


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🟦 TypeScript Tips and Tricks Series (Part 2)

Read Previous Parts: [part 1]

🔣 Higher-Order Types (HOT):

Utilize functions that take and return types, enabling powerful abstractions like generic type predicates and type builders.


type IsStringLiteral<T> = T extends string ? true : false;

function logIfString<T>(value: T): T extends string ? void : T {
if (IsStringLiteral<T>) {
console.log(value);
}
return value;
}


Use Case:
Creating dynamic component that have multiple states and behaviors.


#TypeScript


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📱 JavaScript Quiz

⁉️ What's the output?

const user = {
email: "mail@hmouasvi.dev",
updateEmail: email => {
this.email = email;
}
}

user.updateEmail("new@hmousavi.dev")
console.log(user.email)


🔤 mail@hmousavi.dev
🔤 new@hmousavi.dev
🔤 undefined
🔤 ReferenceError

✔️ Answer:
The updateEmail function is an arrow function, and is not bound to the user object. This means that the this keyword is not referring to the user object, but refers to the global scope in this case. The value of email within the user object does not get updated. When logging the value of user.email, the original value of mail@hmousavi.dev gets returned.


#JavaScript #Quiz


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Software Engineering Quote

💬 Programs must be written with the idea that they will be read by people, and only incidentally for machines to execute.

🔣 Harold Abelson


#Agile #softwareEngineering

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🖼️ CSS Selectors Cheat Sheet

🔣 At its core, CSS is about selecting elements from the DOM to apply styles to them.

Child and Sibling Combinators (+ , ~, >)

/* Child combinator: selects direct children of an element */
.parent > .child {
color: red;
}


Pseudo-Classes (:nth-child(), :nth-of-type(), :not(), :focus, :hover):

.faq-item:nth-of-type(odd) .faq-question{
background-color: #fff; /* For odd items
*/
}


Structural Pseudo-Classes (:first-child, :last-child, :empty, :only-child):

.faq-item:first-of-type .faq-question {
border-top: 2px solid #007BFF;
}


Pseudo-Elements (::before, ::after, ::first-letter, ::first-line):

/* ::after used to display "+" symbol */
.faq-question::after {
content: '+';
color: #00ad8f;
font-size: 1.4em;
}


Attribute Selectors ( [attr^="value"], [attr$="value"], [attr*="value"]):

.faq-item[data-category^="important"] .faq-question {
color: #E91E63;
}


✔️ We will learn more about the use case of each CSS selector in advance later!


📚 Article: [here]
📱 Image Credit: [here]

#css


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🟦 TypeScript Tips and Tricks Series (Part 3)

Previous Parts: [part 1 | Part 2]

🔣 Conditional Types:

Shape types based on conditions, creating dynamic type hierarchies. For example, defining a type that’s an object with specific properties depending on a provided string value.


type Config = {
type: 'basic' | 'advanced';
};

type BasicConfig = Config & { type: 'basic' };
type AdvancedConfig = Config & { type: 'advanced' };

function configure(config: Config): void {
if (config.type === 'basic') {
console.log('Applying basic configuration');
} else {
console.log('Applying advanced configuration');
}
}


Use Case:
Useful for strategy patterns and implementing high-level business logic.


#TypeScript


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🔐 Best Practices For Building Secure FrontEnd Applications

Read Previous Parts: [OSI Layers Review | Common Security Attacks]

✔️ Cultivate a security-focused culture
🔸 Involve all stakeholders in mapping security risks and protections.
🔸 Develop a strong security culture affecting daily procedures and offerings.

✔️ Implement Input/Output Sanitization Strategy
🔸 Validate incoming data at each application stage.
🔸 Use libraries like dom-purify for quicker security implementation.
🔸 Refer to OWASP cheat sheet series for input/output sanitization.

✔️ Regularly examine components and execute a Content Security Policy (CSP)
🔸 Use Software Composition Analysis (SCA) for third-party library security.
🔸 Implement Content-Security-Policy (CSP) for front-end security.

We will learn more about the tools we can use to check our website's security!


📚 Article: [here]

#network #security


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👨‍💻 Best Practices for Code Review


🗣️ Review fewer than 400 lines of code at a time

🗣️ Take your time. Inspection rates should under 500 LOC per hour

🗣️ Foster a positive code review culture


📚 Article: [here]
📱 YouTube Video: [here]

#softwareEngineering #softSkill


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Software Engineering Quote

💬 Code is like humor. When you have to explain it, it’s bad.

🔣 Cory House


#softwareEngineering #programming

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🔺 Code Review Pyramid

Read Previous Parts: [Code Review Best Practices]

🗣️ Each layer of Code Review Pyramid is a characteristic to which the reviewed code must conform.
The bottom layer is the correctness of the code, which is of prime importance.


1️⃣ Code Style
🟢 Consistent naming and formatting.
🔘 Avoid duplication and unused imports.
🟢 Use automatic code formatting tools.

2️⃣ Tests
🟢 Review test cases for coverage.
🔘 Automate testing using plugins.

3️⃣ Documentation
🟢 Keep documentation comprehensive and up-to-date.

4️⃣ Implementation Semantics
🟢 Ensure code meets requirements, is efficient, and secure.
🔘 Check for error handling, resource management, concurrency, and third-party libraries.
🟢 Avoid code smells and anti-patterns.

5️⃣ API Semantics
🟢 Ensure API design follows best practices and provides a clear interface.
🔘 Check for consistency, versioning, error messages, pagination, filtering, and performance.
🟢 Ensure no internal logic leakage, no breaking of existing API, and proper authentication/authorization.

⚠️ Code review shouldn’t proceed to upper layers until the bottom layer, correctness, gets approved.



📚 Article: [here]
🥳 Medium Article: [here]

#softwareEngineering #softSkill


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📱 JavaScript Quiz

⁉️ What's the output?

const box = { x: 10, y: 20 };

Object.freeze(box);

const shape = box;
shape.x = 100;

console.log(shape);


🔤 { x: 100 , y: 20 }
🔤 { x: 10, y: 20 }
🔤 { x: 100 }
🔤 ReferenceError

✔️ Answer: 🔤
Object.freeze prevents adding, removing, or modifying properties of an object (unless the property’s value is another object).

When we create the variable shape and set it equal to the frozen object box, shape also refers to a frozen object. You can check if an object is frozen using Object.isFrozen. In this case, Object.isFrozen(shape) returns true.

Since shape is frozen and x is not an object, we cannot modify x. Therefore, x remains 10, and { x: 10, y: 20 } gets logged.



#JavaScript #Quiz


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🖼️ Angular 18 Release Changes!


🔣 Release Highlights:

Experimental support for zoneless change detection.
Angular.dev is the new home for Angular developers.
Material 3, deferrable views, built-in control flow are now stable.
Server-side rendering improvements: i18n hydration support, better debugging, event replay.

🔣 Other Release Features:

Zoneless Change Detection
Native await for Zoneless Apps
Components Support Zoneless
Signal APIs in Developer Preview
Firebase App Hosting



🖼️ My LinkedIn Post With Full Details: [here]
🥳 Medium Article: [here]
🖼️ YouTube Video: [here]

#angular


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Software Engineering Quote

💬 Even the most complex systems are inherently simple when viewed from the right angle.

🔣 Eliyahu M. Goldratt


#softwareEngineering #systemDesign

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🟦 TypeScript Tips and Tricks Series (Part 4)

Previous Parts: [part 1 | Part 2 | Part 3]

🔣 Mapped Types

Transform existing types by applying operations to each property. Useful for adding prefixes/suffixes to properties, creating key-value pairs from objects, etc.


interface User {
name: string;
age: number;
}

type ReadOnly<T> = { readonly [P in keyof T]: T[P] };

const readOnlyUser: ReadOnly<User> = {
name: 'Kurt',
age: 27
};

// readOnlyUser.name = 'Chester';
// Error: Cannot assign to 'name' because it is a read-only property


Use Case:
Useful for manipulate and transform data from the API or before passing data to another component, with different data types.


#TypeScript


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🖥 Difference Between Encryption, Encoding, Hashing, Obfuscation


💬 Encoding
✔️ Encoding is for maintaining data usability and can be reversed by employing the same algorithm that encoded the content, i.e. no key is used.


💬 Encryption
✔️ Encryption is for maintaining data confidentiality and requires the use of a key (kept secret) in order to return to plaintext.


💬 Hashing
✔️ Hashing is for validating the integrity of content by detecting all modification thereof via obvious changes to the hash output.


💬 Obfuscation
✔️ Obfuscation is used to prevent people from understanding the meaning of something, and is often used with computer code to help prevent successful reverse engineering and/or theft of a product’s functionality.



📚 Article: [here]
🥳 Medium Article: [here]
🖼️ YouTube Video: [here]

#softwareEngineering #security


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