JavaScript is a powerful and versatile programming language, and if you master smart coding techniques, your development speed and code efficiency can improve significantly. One-liners are short yet powerful code snippets that make common tasks easier and faster.
Today, we’ll explore 10 mind-blowing JavaScript one-liners that have real-world applications. If you’re a developer, coder, or JavaScript enthusiast, these tricks will take your coding game to the next level! 🔥
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1️⃣ Convert an Array of Objects into a JSON.
📌 Use Case: When you need to convert API-fetched data into object format, like in user management systems or e-commerce orders.
const users = [{id: 1, name: "Aman"}, {id: 2, name: "Neha"}];
const userObj = Object.fromEntries(users.map(user => [user.id, user]));
console.log(userObj);
// ✅ Output:
{
"1": {"id": 1, "name": "Aman"},
"2": {"id": 2, "name": "Neha"}
}
💡 What Did We Learn?
map()iterates through the array and setsidas the key.Object.fromEntries()generates a new object from key-value pairs.
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2️⃣ Remove Duplicates from an Array 🔥
📌 Use Case: When you need to remove duplicate values from product tags, categories, or customer preferences.
const tags = ["sale", "new", "sale", "trending"];
const uniqueTags = [...new Set(tags)];
console.log(uniqueTags);
// ✅ Output:
[ "sale", "new", "trending" ]
💡 What Did We Learn?
Set()automatically removes duplicates.[...Set]uses the spread operator to convert Set back into an array.
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3️⃣ Swap Two Variables Without a Third Variable 🔥
📌 Use Case: When you need to swap values in form validation or data manipulation.
let a = 5, b = 10;
[a, b] = [b, a];
console.log(a, b);
// ✅ Output: 10, 5
💡 What Did We Learn?
- Uses ES6 destructuring for clean & readable syntax.
- No need for an extra variable.
- Works with any type of variables (numbers, strings, objects).
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5️⃣ Flatten a Nested Array (Multi-Level) 🔥
📌 Use Case: When you need to flatten JSON API responses.
const nestedArr = [1, [2, [3, [4]]]];
const flatArr = nestedArr.flat(Infinity);
console.log(flatArr);
// ✅ Output:
[1, 2, 3, 4]
✅ Why use this?
- Easy and readable!
- Supports any depth (
Infinityensures full flattening). - Best choice for modern JavaScript (ES2019+).
❌ Limitation:
- Doesn’t work in older browsers (Polyfill required).
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6️⃣ Generate a Random Hex Color 🎨
📌 Use Case: When you need to generate random colors for UI themes or design applications.
const randomColor = () => "#" + Math.floor(Math.random() * 16777215).toString(16).padStart(6, '0');
console.log(randomColor());
// ✅ Output: - Any Random Hexa Color Code...
✅ Why is this the best?
**Math.random() * 0xFFFFFF**→ Generates a random number between 0 and 16777215 (decimal forFFFFFF).**.toString(16)**→ Converts the number to a hexadecimal string.**.padStart(6, '0')**→ Ensures the color always has 6 characters.
🔥 Guaranteed to always return a valid hex color!
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7️⃣ Get the Last Element of an Array 🔥
📌 Use Case: When you need to fetch the last message in chat applications or notifications.
const lastElement = arr => arr.at(-1);
console.log(lastElement([5, 10, 15, 20]));
// ✅ Output: 20
✅ Why use this?
- Works with negative indexes.
- Cleaner and more readable.
- Best for modern JavaScript (ES2022+).
❌ Limitation:
- Doesn’t work in older browsers (Polyfill needed).
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8️⃣ Reverse a String in One Line 🔥
📌 Use Case: When you need to implement CAPTCHA validation or reverse text animation.
const reverseString = str => [...str].reverse().join("");
console.log(reverseString("hello"));
// ✅ Output: "olleh"
🚀 How Does This Work?
**split("")**→ Converts the string into an array of characters.
— “Hello” => [“H”, “e”, “l”, “l”, “o”]**reverse()**→ Reverses the array order.
— [“o”, “l”, “l”, “e”, “H”]**join("")**→ Converts the array back into a string.
— “olleH”
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9️⃣ Count the Occurrences of Each Element in an Array 🔥
📌 Use Case: When you need to track best-selling products in an e-commerce website.
const countOccurrences = arr => arr.reduce((acc, val) => (acc[val] = (acc[val] || 0) + 1, acc), {});
console.log(countOccurrences(["apple", "banana", "apple", "orange", "banana", "apple"]));
// ✅ Output: { apple: 3, banana: 2, orange: 1 }
✅ Why use this?
- Efficient & concise ✅
- Works for any type of array values ✅
- No extra loops ✅
⚠ Limitation:
- Might be less readable for beginners.
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🔟 Check if an Object is Empty 🔥
📌 Use Case: When you need to validate API responses or form inputs.
const isEmptyObject = obj => Object.keys(obj).length === 0;
console.log(isEmptyObject({}));
console.log(isEmptyObject({ name: "John" }));
// ✅ Output:
- True
- False
✅ Why use this?
Object.keys(obj)returns an array of keys.- If length is
**0**, the object is empty. - Works in all browsers (including old ones).
⚠ Limitation:
- Only checks own properties, not inherited properties.
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🚀 Conclusion
Efficiency and readability are crucial in JavaScript. These 10 powerful one-liners will help you write faster, cleaner, and smarter code.
🛠 Which one-liner did you find the most useful? Drop a comment below! 💬