Top 50 One-Liners JavaScript
Tags: javascript, webdev, beginners, programming
Published: 2024-02-13 12:39:04

**Mastering JavaScript: Top 50 One-Liners Every Developer Should Know**

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**Introduction:**

JavaScript is a versatile and powerful programming language used extensively in web development. Whether you're a seasoned developer or just starting your journey, mastering JavaScript can significantly boost your productivity and efficiency. In this article, we'll explore the top 50 JavaScript one-liners that every developer should know. These concise and elegant solutions cover a wide range of common tasks, from manipulating arrays to working with strings and objects.

**1. Checking if a Variable is Undefined:**
```javascript
const isUndefined = variable => typeof variable === 'undefined';
```

**2. Checking if a Variable is Null:**
```javascript
const isNull = variable => variable === null;
```

**3. Checking if a Variable is Empty:**
```javascript
const isEmpty = variable => !variable;
```

**4. Checking if a Variable is an Array:**
```javascript
const isArray = variable => Array.isArray(variable);
```

**5. Checking if a Variable is an Object:**
```javascript
const isObject = variable => typeof variable === 'object' && variable !== null;
```

**6. Checking if a Variable is a Function:**
```javascript
const isFunction = variable => typeof variable === 'function';
```

**7. Getting the Last Element of an Array:**
```javascript
const lastElement = array => array.slice(-1)[0];
```

**8. Flattening an Array:**
```javascript
const flattenArray = array => array.flat();
```

**9. Reversing a String:**
```javascript
const reverseString = str => str.split('').reverse().join('');
```

**10. Generating a Random Number:**
```javascript
const randomNumber = (min, max) => Math.floor(Math.random() * (max - min + 1)) + min;
```

**11. Removing Duplicates from an Array:**
```javascript
const removeDuplicates = array => [...new Set(array)];
```

**12. Checking if an Array Contains a Specific Value:**
```javascript
const containsValue = (array, value) => array.includes(value);
```

**13. Checking if a String Contains a Substring:**
```javascript
const containsSubstring = (str, substring) => str.includes(substring);
```

**14. Getting the Current Date and Time:**
```javascript
const currentDateTime = () => new Date().toLocaleString();
```

**15. Checking if a Year is a Leap Year:**
```javascript
const isLeapYear = year => (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0;
```

**16. Truncating a Number to a Specified Decimal Place:**
```javascript
const truncateNumber = (num, decimalPlaces) => Math.trunc(num * 10 ** decimalPlaces) / 10 ** decimalPlaces;
```

**17. Checking if an Object has a Specific Property:**
```javascript
const hasProperty = (obj, property) => obj.hasOwnProperty(property);
```

**18. Converting a String to Title Case:**
```javascript
const toTitleCase = str => str.replace(/\b\w/g, char => char.toUpperCase());
```

**19. Repeating a String N Times:**
```javascript
const repeatString = (str, n) => str.repeat(n);
```

**20. Generating a Range of Numbers:**
```javascript
const range = (start, end) => Array.from({ length: end - start + 1 }, (_, i) => start + i);
```

**21. Summing Numbers in an Array:**
```javascript
const sumArray = array => array.reduce((acc, curr) => acc + curr, 0);
```

**22. Getting the Maximum Value in an Array:**
```javascript
const maxArrayValue = array => Math.max(...array);
```

**23. Getting the Minimum Value in an Array:**
```javascript
const minArrayValue = array => Math.min(...array);
```

**24. Checking if a Number is Even:**
```javascript
const isEven = num => num % 2 === 0;
```

**25. Checking if a Number is Odd:**
```javascript
const isOdd = num => num % 2 !== 0;
```

**26. Checking if a String is Palindrome:**
```javascript
const isPalindrome = str => str === str.split('').reverse().join('');
```

**27. Reversing the Order of Words in a String:**
```javascript
const reverseWords = str => str.split(' ').reverse().join(' ');
```

**28. Checking if a Number is Prime:**
```javascript
const isPrime = num => {
    for (let i = 2; i <= Math.sqrt(num); i++) {
        if (num % i === 0) return false;
    }
    return num > 1;
};
```

**29. Converting Fahrenheit to Celsius:**
```javascript
const fahrenheitToCelsius = f => (f - 32) * 5 / 9;
```

**30. Converting Celsius to Fahrenheit:**
```javascript
const celsiusToFahrenheit = c => (c * 9 / 5) + 32;
```

**31. Factorial of a Number:**
```javascript
const factorial = n => n === 0 ? 1 : n * factorial(n - 1);
```

**32. Fibonacci Sequence:**
```javascript
const fibonacci = n => n <= 1 ? n : fibonacci(n - 1) + fibonacci(n - 2);
```

**33. Finding the Greatest Common Divisor (GCD) of Two Numbers:**
```javascript
const gcd = (a, b) => b === 0 ? a : gcd(b, a % b);
```

**34. Finding the Least Common Multiple (LCM) of Two Numbers:**
```javascript
const lcm = (a, b) => (a * b) / gcd(a, b);
```

**34. Shuffle an Array:**
```javascript
const shuffleArray = array => array.sort(() => Math.random() - 0.5);
```

**35. Checking if a Number is a Perfect Square:**
```javascript
const isPerfectSquare = num => Math.sqrt(num) % 1 === 0;
```

**36. Checking if a Number is a Power of Two:**
```javascript
const isPowerOfTwo = num => (num & (num - 1)) === 0 && num !== 0;
```

**37. Checking if a Number is a Palindrome:**
```javascript
const isPalindromeNumber = num => num.toString() === num.toString().split('').reverse().join('');
```

**38. Capitalize the First Letter of Each Word in a Sentence:**
```javascript
const capitalizeWords = sentence => sentence.replace(/\b\w/g, char => char.toUpperCase());
```

**39. Counting the Occurrences of Each Element in an Array:**
```javascript
const countOccurrences = array => array.reduce((acc, val) => {
  acc[val] = (acc[val] || 0) + 1;
  return acc;
}, {});
```



**40. Sum of Squares of Digits of a Number:**
```javascript
const sumOfSquareDigits = num => num.toString().split('').reduce((acc, digit) => acc + Math.pow(parseInt(digit), 2), 0);
```


**41. Converting a Number to Binary:**
```javascript
const toBinary = num => num.toString(2);
```

**42. Converting a Binary Number to Decimal:**
```javascript
const binaryToDecimal = binary => parseInt(binary, 2);
```

**43. Checking if a String is an Anagram of Another String:**
```javascript
const isAnagram = (str1, str2) => str1.split('').sort().join('') === str2.split('').sort().join('');
```

**44. Converting an Object to Query Parameters String:**
```javascript
const objectToQueryString = obj => Object.entries(obj).map(([key, value]) => `${encodeURIComponent(key)}=${encodeURIComponent(value)}`).join('&');
```

**45. Checking if a Year is a Leap Year (Using Ternary Operator):**
```javascript
const isLeapYear = year => (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0 ? true : false;
```

**46. Reversing an Array in Place:**
```javascript
const reverseArrayInPlace = array => array.reverse();
```

**47. Finding the Maximum Value in an Array (Using Spread Operator):**
```javascript
const maxArrayValue = array => Math.max(...array);
```

**48. Finding the Minimum Value in an Array (Using Spread Operator):**
```javascript
const minArrayValue = array => Math.min(...array);
```

**49. Truncating a String to a Maximum Length and Appending Ellipsis:**
```javascript
const truncateString = (str, maxLength) => str.length > maxLength ? str.slice(0, maxLength) + '...' : str;
```

**50. Finding the Longest Word in a Sentence:**
```javascript
const longestWord = sentence => sentence.split(' ').reduce((longest, current) => current.length > longest.length ? current : longest, '');
```

**Conclusion:**
JavaScript one-liners are concise and powerful solutions to common programming tasks. By mastering these one-liners, you can write cleaner, more efficient code and become a more proficient JavaScript developer. Experiment with these examples and incorporate them into your projects to take your coding skills to the next level. Happy coding!