👉 Part 1 -> 🔥Handy Copy-Paste Javascript Snippets Part 1 👉 Part 2 -> 🔥Handy Copy-Paste Javascript Snippets Part 2

Strings

Check if a path is relative

js
const isRelative = (path) => !/^([a-z]+:)?[\\/]/i.test(path); // Examples
isRelative("/foo/bar/baz"); // false
isRelative("C:\\foo\\bar\\baz"); // false
isRelative("foo/bar/baz.txt"); // true
isRelative("foo.md"); // true

Make the first character of a string lowercase

js
const lowercaseFirst = (str) => `${str.charAt(0).toLowerCase()}${str.slice(1)}`;
// Example
lowercaseFirst("Hello World"); // 'hello World'

Repeat a string

js
const repeat = (str, numberOfTimes) => str.repeat(numberOfTimes);

Check if a string is a hexadecimal color

js
const isHexColor = (color) =>
  /^#([0-9A-F]{3}|[0-9A-F]{4}|[0-9A-F]{6}|[0-9A-F]{8})$/i.test(color); // Examples
isHexColor("#012"); // true
isHexColor("#A1B2C3"); // true
isHexColor("012"); // false
isHexColor("#GHIJKL"); // false

Dates

Add “am/pm” suffix to an hour

js
// `h` is an hour number between 0 and 23
const suffixAmPm = (h) =>
  `${h % 12 === 0 ? 12 : h % 12}${h < 12 ? "am" : "pm"}`; // Examples
suffixAmPm(0); // '12am'
suffixAmPm(5); // '5am'
suffixAmPm(12); // '12pm'
suffixAmPm(15); // '3pm'
suffixAmPm(23); // '11pm'

Calculate the number of different days between two dates

js
const diffDays = (date, otherDate) =>
  Math.ceil(Math.abs(date - otherDate) / (1000 * 60 * 60 * 24)); // Example
diffDays(new Date("2014-12-19"), new Date("2020-01-01")); // 1839

Check if a date is valid

js
const isDateValid = (...val) => !Number.isNaN(new Date(...val).valueOf());
isDateValid("December 17, 1995 03:24:00"); // true

Miscellaneous

Check if the code is running in Node.js

js
const isNode =
  typeof process !== "undefined" &&
  process.versions != null &&
  process.versions.node != null;

Check if the code is running in the browser

js
const isBrowser = typeof window === "object" && typeof document === "object";

Convert URL parameters to object

js
const getUrlParams = (query) =>
  Array.from(new URLSearchParams(query)).reduce(
    (p, [k, v]) =>
      Object.assign({}, p, {
        [k]: p[k] ? (Array.isArray(p[k]) ? p[k] : [p[k]]).concat(v) : v,
      }),
    {}
  ); // Examples
getUrlParams(location.search); // Get the parameters of the current URLgetUrlParams('foo=Foo&bar=Bar'); // { foo: "Foo", bar: "Bar" }// Duplicate key
getUrlParams("foo=Foo&foo=Fuzz&bar=Bar"); // { foo: ["Foo", "Fuzz"], bar: "Bar" }

Detect dark mode

js
const isDarkMode =
  window.matchMedia &&
  window.matchMedia("(prefers-color-scheme: dark)").matches;

Swap two variables

js
[a, b] = [b, a];

Copy to clipboard

js
const copyToClipboard = (text) => navigator.clipboard.writeText(text); // Example
copyToClipboard("Hello World");

Convert RGB to Hex

js
const rgbToHex = (r, g, b) =>
  "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1); // Example
rgbToHex(0, 51, 255); // #0033ff

Generate a random hex color

js
const randomColor = () =>
  `#${Math.random().toString(16).slice(2, 8).padEnd(6, "0")}`; // Or
const randomColor = () => `#${(~~(Math.random() * (1 << 24))).toString(16)}`;

Generate a random IP address

js
const randomIp = () =>
  Array(4)
    .fill(0)
    .map((_, i) => Math.floor(Math.random() * 255) + (i === 0 ? 1 : 0))
    .join("."); // Example
randomIp(); // 175.89.174.131

Generate a random string using the Node crypto module

js
const randomStr = () => require("crypto").randomBytes(32).toString("hex");

Conclusion

Don’t forget to clap 👏 in the comment section below if you learned something new