⚠️ Common JavaScript Issues Every Developer Faces (And How to Fix Them)

⚠️ Common JavaScript Issues Every Developer Faces (And How to Fix Them)

JavaScript is awesome — but sometimes it feels like it’s actively trying to break your brain. Here's a list of common issues (and how to survive them).

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1. ❌ undefined vs null

let x;        // undefined  
let y = null; // explicitly null  

• undefined means a variable was declared but not assigned.
• null means you deliberately emptied it.

🛠 Fix: Know when to use each and initialize your variables properly.

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2. 🧮 Loose vs Strict Equality

0 == false   // true  
0 === false  // false  

• == does type coercion.
• === checks both value and type.

🛠 Fix: Always prefer === and !==.

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3. 🌀 The this Keyword Trap

const person = {
  name: "Yuri",
  greet() {
    console.log("Hi, I'm " + this.name);
  }
};

Arrow functions don’t bind this the way you expect in object methods.

🛠 Fix: Use traditional functions in objects or .bind(this) if needed.

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4. 🔄 Async/Await Abuse

async function fetchData() {
  const res = await fetch("/api/data");
  const data = await res.json();
  return data;
}

🛠 Fix: Stick with async/await for readability. Don’t mix with .then() unless necessary.

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5. 📦 Undeclared Variables

x = 10; // global leak 😡  

🛠 Fix: Use let, const, or var to declare variables.

let x = 10;

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6. 🔁 Loop Scope Issues

for (var i = 0; i < 3; i++) {
  setTimeout(() => console.log(i), 100);
}
// Outputs: 3, 3, 3

🛠 Fix: Use let:

for (let i = 0; i < 3; i++) {
  setTimeout(() => console.log(i), 100);
}
// Outputs: 0, 1, 2

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7. 🧼 No Error Handling in Promises

fetch("/api").then(res => res.json()).then(data => console.log(data));

🛠 Fix: Use .catch() or a try/catch block with async/await:

async function safeFetch() {
  try {
    const res = await fetch("/api");
    const data = await res.json();
    console.log(data);
  } catch (error) {
    console.error("Something went wrong!", error);
  }
}

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✅ Final Advice

• Use a linter like ESLint
• Write unit tests
• Use "use strict"; mode
• TypeScript is your friend 👀

Happy hacking, JavaScript warrior 🛡️💥

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Javascript Sucks