25+ Essential JavaScript One-Liners You Need to Know in 2025

Hello Devs! Welcome back to another article. JavaScript continues to evolve, providing developers with more concise and efficient ways to write code. Whether you're an experienced programmer or just starting your journey, mastering these modern one-liners can significantly enhance your productivity. These modern JavaScript one-liners will streamline your development workflow in 2025, helping you write cleaner, faster, and more efficient code. Array Manipulations 1. Find the Maximum Value in an Array Math.max(...array); Uses the spread operator to pass elements as arguments to Math.max(). 2. Remove Duplicates from an Array [...new Set(array)]; Converts the array to a Set (which removes duplicates) and back to an array. 3. Flatten a Nested Array const flatten = (arr) => arr.flat(Infinity); Flattens an array to any depth using flat(Infinity). 4. Get a Random Element from an Array const randomElement = (arr) => arr[Math.floor(Math.random() * arr.length)]; Selects a random element from an array. 5. Get the Last Item of an Array const lastItem = (arr) => arr.at(-1); Uses .at(-1) for cleaner syntax to get the last element. 6. Get the First N Elements of an Array const firstN = (arr, n) => arr.slice(0, n); Extracts the first n elements from an array. Object Utilities 7. Check if an Object is Empty const isEmptyObject = (obj) => Object.keys(obj).length === 0; Returns true if the object has no properties. 8. Merge Multiple Objects const mergeObjects = (...objs) => Object.assign({}, ...objs); Combines multiple objects into one. 9. Deep Clone an Object const clone = (obj) => structuredClone(obj); Uses the built-in structuredClone() method for deep cloning. 10. Convert an Object to an Array const objToArray = (obj) => Object.entries(obj); Turns an object into an array of key-value pairs. 11. Get Unique Elements from an Array of Objects (by Property) const uniqueBy = (arr, key) => [...new Map(arr.map(item => [item[key], item])).values()]; Filters unique objects based on a specific property. String Operations 12. Capitalize the First Letter of a String const capitalize = (str) => str.charAt(0).toUpperCase() + str.slice(1); Capitalizes only the first letter while keeping the rest unchanged. 13. Convert a String to a Slug const slugify = (str) => str.toLowerCase().trim().replace(/\s+/g, '-'); Replaces spaces with hyphens and ensures lowercase formatting. 14. Reverse a String const reverseString = (str) => [...str].reverse().join(''); Splits the string into an array, reverses it, and joins it back. 15. Count Occurrences of a Character in a String const countChar = (str, char) => str.split(char).length - 1; Counts how many times a specific character appears in a string. 16. Check if a String Contains a Substring (Case Insensitive) const containsIgnoreCase = (str, substr) => str.toLowerCase().includes(substr.toLowerCase()); Performs a case-insensitive substring check. 17. Generate a Random Alphanumeric String const randomAlphaNum = (length) => [...Array(length)].map(() => (Math.random().toString(36)[2])).join(''); Generates a random alphanumeric string of a given length. Utility Functions 18. Get the Current Timestamp Date.now(); Returns the current timestamp in milliseconds. 19. Check if a Variable is an Array Array.isArray(variable); Returns true if the variable is an array. 20. Convert Query Parameters to an Object const parseQuery = (url) => Object.fromEntries(new URL(url).searchParams); Parses query parameters from a URL into an object. 21. Format a Date in YYYY-MM-DD Format const formatDate = (date) => date.toISOString().split('T')[0]; Extracts the date portion from an ISO date string. 22. Shorten an Array by Removing Falsy Values const cleanArray = (arr) => arr.filter(Boolean); Removes false, 0, null, undefined, NaN, and "" from an array. Randomization & Color Utilities 23. Generate a Random Integer Between Two Values (Inclusive) const randomBetween = (min, max) => Math.floor(Math.random() * (max - min + 1)) + min; Efficiently generates a random number within the specified range. 24. Generate a Random HEX Color const randomHexColor = () => `#${Math.floor(Math.random() * 0xffffff).toString(16).padStart(6, '0')}`; Generates a random hexadecimal color code. 25. Convert RGB to HEX const rgbToHex = (r, g, b) => `#${((1

Math.max(...array);

[...new Set(array)];

const flatten = (arr) => arr.flat(Infinity);

const randomElement = (arr) => arr[Math.floor(Math.random() * arr.length)];

const lastItem = (arr) => arr.at(-1);

const firstN = (arr, n) => arr.slice(0, n);

const isEmptyObject = (obj) => Object.keys(obj).length === 0;

const mergeObjects = (...objs) => Object.assign({}, ...objs);

const clone = (obj) => structuredClone(obj);

const objToArray = (obj) => Object.entries(obj);

const uniqueBy = (arr, key) => [...new Map(arr.map(item => [item[key], item])).values()];

const capitalize = (str) => str.charAt(0).toUpperCase() + str.slice(1);

const slugify = (str) => str.toLowerCase().trim().replace(/\s+/g, '-');

const reverseString = (str) => [...str].reverse().join('');

const countChar = (str, char) => str.split(char).length - 1;

const containsIgnoreCase = (str, substr) => str.toLowerCase().includes(substr.toLowerCase());

const randomAlphaNum = (length) => [...Array(length)].map(() => (Math.random().toString(36)[2])).join('');

Date.now();

Array.isArray(variable);

const parseQuery = (url) => Object.fromEntries(new URL(url).searchParams);

const formatDate = (date) => date.toISOString().split('T')[0];

const cleanArray = (arr) => arr.filter(Boolean);

const randomBetween = (min, max) => Math.floor(Math.random() * (max - min + 1)) + min;

const randomHexColor = () => `#${Math.floor(Math.random() * 0xffffff).toString(16).padStart(6, '0')}`;

const rgbToHex = (r, g, b) => `#${((1 << 24) | (r << 16) | (g << 8) | b).toString(16).slice(1)}`;

const uuid = () => crypto.randomUUID();

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