JavaScript Methods

let str = "Hello, World!";
 
// charAt()
console.log(str.charAt(0)); // "H"
 
// charCodeAt()
console.log(str.charCodeAt(0)); // 72
 
// codePointAt() (ES2015)
console.log(str.codePointAt(0)); // 72
 
// concat()
console.log(str.concat(" Welcome!")); // "Hello, World! Welcome!"
 
// endsWith() (ES2015)
console.log(str.endsWith("!")); // true
 
// includes() (ES2016)
console.log(str.includes("World")); // true
 
// indexOf()
console.log(str.indexOf("o")); // 4
 
// lastIndexOf()
console.log(str.lastIndexOf("o")); // 8
 
// localeCompare()
console.log(str.localeCompare("Hello")); // 1
 
// match()
console.log(str.match(/o/g)); // ["o", "o"]
 
// matchAll() (ES2020)
console.log(Array.from(str.matchAll(/o/g))); // [["o"], ["o"]]
 
// normalize() (ES2015)
let accented = "é";
console.log(accented.normalize("NFD")); // "é"
 
// padEnd() (ES2017)
console.log(str.padEnd(20, '.')); // "Hello, World!....."
 
// padStart() (ES2017)
console.log(str.padStart(20, '.')); // ".....Hello, World!"
 
// repeat() (ES2015)
console.log(str.repeat(2)); // "Hello, World!Hello, World!"
 
// replace()
console.log(str.replace("World", "Universe")); // "Hello, Universe!"
 
// replaceAll() (ES2021)
console.log(str.replaceAll("o", "0")); // "Hell0, W0rld!"
 
// search()
console.log(str.search("World")); // 7
 
// slice()
console.log(str.slice(7, 12)); // "World"
 
// split()
console.log(str.split(", ")); // ["Hello", "World!"]
 
// startsWith() (ES2015)
console.log(str.startsWith("Hello")); // true
 
// substring()
console.log(str.substring(7, 12)); // "World"
 
// toLowerCase()
console.log(str.toLowerCase()); // "hello, world!"
 
// toUpperCase()
console.log(str.toUpperCase()); // "HELLO, WORLD!"
 
// trim()
let paddedStr = "   Hello, World!   ";
console.log(paddedStr.trim()); // "Hello, World!"
 
// trimEnd() (ES2019)
console.log(paddedStr.trimEnd()); // "   Hello, World!"
 
// trimStart() (ES2019)
console.log(paddedStr.trimStart()); // "Hello, World!   "

let arr = [1, 2, 3, 4];
 
// at() (ES2022)
console.log(arr.at(-1)); // 4
 
// concat()
console.log(arr.concat([5, 6])); // [1, 2, 3, 4, 5, 6]
 
// copyWithin() (ES2015)
console.log(arr.copyWithin(1, 2)); // [1, 3, 4, 4]
 
// entries() (ES2015)
console.log(Array.from(arr.entries())); // [[0, 1], [1, 3], [2, 4], [3, 4]]
 
// every()
console.log(arr.every(num => num > 0)); // true
 
// fill() (ES2015)
console.log(arr.fill(0, 1, 3)); // [1, 0, 0, 4]
 
// filter()
console.log(arr.filter(num => num > 2)); // [4, 4]
 
// find() (ES2015)
console.log(arr.find(num => num > 2)); // 4
 
// findIndex() (ES2015)
console.log(arr.findIndex(num => num > 2)); // 2
 
// findLast() (ES2023)
console.log(arr.findLast(num => num > 2)); // 4
 
// findLastIndex() (ES2023)
console.log(arr.findLastIndex(num => num > 2)); // 3
 
// flat() (ES2019)
let nested = [1, [2, [3, [4]]]];
console.log(nested.flat(2)); // [1, 2, 3, [4]]
 
// flatMap() (ES2019)
console.log(arr.flatMap(x => [x * 2])); // [2, 0, 0, 8]
 
// forEach()
arr.forEach(num => console.log(num)); // 1 0 0 4
 
// includes() (ES2016)
console.log(arr.includes(2)); // false
 
// indexOf()
console.log(arr.indexOf(4)); // 3
 
// join()
console.log(arr.join("-")); // "1-0-0-4"
 
// keys() (ES2015)
console.log(Array.from(arr.keys())); // [0, 1, 2, 3]
 
// map()
console.log(arr.map(num => num * num)); // [1, 0, 0, 16]
 
// pop()
console.log(arr.pop()); // 4
 
// push()
console.log(arr.push(5)); // 4 (new length)
 
// reduce()
console.log(arr.reduce((total, num) => total + num)); // 1
 
// reduceRight()
console.log(arr.reduceRight((total, num) => total + num)); // 1
 
// reverse()
console.log(arr.reverse()); // [0, 0, 1]
 
// shift()
console.log(arr.shift()); // 0
 
// slice()
console.log(arr.slice(1, 3)); // [0, 1]
 
// some()
console.log(arr.some(num => num > 0)); // true
 
// sort()
console.log(arr.sort((a, b) => a - b)); // [0, 0, 1]
 
// splice()
console.log(arr.splice(1, 1, 5)); // [0] (removed element)
console.log(arr); // [0, 5, 1]
 
// toLocaleString()
console.log(arr.toLocaleString()); // "0,5,1"
 
// toString()
console.log(arr.toString()); // "0,5,1"
 
// unshift()
console.log(arr.unshift(-1)); // 4 (new length)
console.log(arr); // [-1, 0, 5, 1]
 
// values() (ES2015)
console.log(Array.from(arr.values())); // [-1, 0, 5, 1]

let target = { a: 1 };
let source = { b: 2, c: 3 };
 
// assign() (ES2015)
console.log(Object.assign(target, source)); // { a: 1, b: 2, c: 3 }
 
// create()
let proto = { greet: function() { return "Hello"; } };
let obj = Object.create(proto);
console.log(obj.greet()); // "Hello"
 
// defineProperties()
Object.defineProperties(target, {
  d: { value: 4, writable: true },
  e: { value: 5, writable: false }
});
console.log(target); // { a: 1, b: 2, c: 3, d: 4, e: 5 }
 
// defineProperty()
Object.defineProperty(target, "f", {
  value: 6,
  writable: false
});
console.log(target); // { a: 1, b: 2, c: 3, d: 4, e: 5, f: 6 }
 
// entries() (ES2017)
console.log(Object.entries(target)); // [["a", 1], ["b", 2], ["c", 3], ["d", 4], ["e", 5], ["f", 6]]
 
// freeze()
Object.freeze(target);
target.a = 42; // No effect
console.log(target.a); // 1
 
// fromEntries() (ES2019)
let entries = [["a", 1], ["b", 2]];
let objFromEntries = Object.fromEntries(entries);
console.log(objFromEntries); // { a: 1, b: 2 }
 
// getOwnPropertyDescriptor()
console.log(Object.getOwnPropertyDescriptor(target, "a")); // { value: 1, writable: true, enumerable: true, configurable: true }
 
// getOwnPropertyDescriptors() (ES2017)
console.log(Object.getOwnPropertyDescriptors(target));
 
// getOwnPropertyNames()
console.log(Object.getOwnPropertyNames(target)); // ["a", "b", "c", "d", "e", "f"]
 
// getOwnPropertySymbols()
let sym = Symbol("sym");
target[sym] = "symbolValue";
console.log(Object.getOwnPropertySymbols(target)); // [Symbol(sym)]
 
// getPrototypeOf()
console.log(Object.getPrototypeOf(target)); // {}
 
// hasOwn() (ES2022)
console.log(Object.hasOwn(target, "a")); // true
 
// is() (ES2015)
console.log(Object.is(25, 25)); // true
 
// isExtensible()
console.log(Object.isExtensible(target)); // false
 
// isFrozen()
console.log(Object.isFrozen(target)); // true
 
// isSealed()
console.log(Object.isSealed(target)); // true
 
// keys()
console.log(Object.keys(target)); // ["a",
 
 "b", "c", "d", "e", "f"]
 
// preventExtensions()
Object.preventExtensions(source);
console.log(Object.isExtensible(source)); // false
 
// seal()
Object.seal(target);
target.g = 7; // No effect
delete target.a; // No effect
console.log(target); // { a: 1, b: 2, c: 3, d: 4, e: 5, f: 6 }
 
// setPrototypeOf()
Object.setPrototypeOf(target, proto);
console.log(target.greet()); // "Hello"
 
// values() (ES2017)
console.log(Object.values(target)); // [1, 2, 3, 4, 5, 6]

// abs()
console.log(Math.abs(-4.5)); // 4.5
 
// acos()
console.log(Math.acos(1)); // 0
 
// acosh() (ES2015)
console.log(Math.acosh(1)); // 0
 
// asin()
console.log(Math.asin(0)); // 0
 
// asinh() (ES2015)
console.log(Math.asinh(0)); // 0
 
// atan()
console.log(Math.atan(0)); // 0
 
// atanh() (ES2015)
console.log(Math.atanh(0)); // 0
 
// atan2()
console.log(Math.atan2(0, 1)); // 0
 
// cbrt() (ES2015)
console.log(Math.cbrt(8)); // 2
 
// ceil()
console.log(Math.ceil(4.2)); // 5
 
// clz32() (ES2015)
console.log(Math.clz32(1)); // 31
 
// cos()
console.log(Math.cos(0)); // 1
 
// cosh() (ES2015)
console.log(Math.cosh(0)); // 1
 
// exp()
console.log(Math.exp(1)); // 2.718281828459045
 
// expm1() (ES2015)
console.log(Math.expm1(1)); // 1.718281828459045
 
// floor()
console.log(Math.floor(4.7)); // 4
 
// fround() (ES2015)
console.log(Math.fround(1.337)); // 1.3370000123977661
 
// hypot() (ES2015)
console.log(Math.hypot(3, 4)); // 5
 
// imul() (ES2015)
console.log(Math.imul(2, 3)); // 6
 
// log()
console.log(Math.log(10)); // 2.302585092994046
 
// log1p() (ES2015)
console.log(Math.log1p(0)); // 0
 
// log2()
console.log(Math.log2(8)); // 3
 
// log10()
console.log(Math.log10(100)); // 2
 
// max()
console.log(Math.max(1, 2, 3)); // 3
 
// min()
console.log(Math.min(1, 2, 3)); // 1
 
// pow()
console.log(Math.pow(2, 3)); // 8
 
// random()
console.log(Math.random()); // Random number between 0 and 1
 
// round()
console.log(Math.round(4.5)); // 5
 
// sign() (ES2015)
console.log(Math.sign(-5)); // -1
 
// sinh() (ES2015)
console.log(Math.sinh(0)); // 0
 
// sqrt()
console.log(Math.sqrt(16)); // 4
 
// tan()
console.log(Math.tan(0)); // 0
 
// tanh() (ES2015)
console.log(Math.tanh(0)); // 0
 
// trunc() (ES2015)
console.log(Math.trunc(4.9)); // 4

let date = new Date();
 
// getDate()
console.log(date.getDate()); // Current day of the month
 
// getDay()
console.log(date.getDay()); // Day of the week (0-6)
 
// getFullYear()
console.log(date.getFullYear()); // Current year
 
// getHours()
console.log(date.getHours()); // Current hour
 
// getMinutes()
console.log(date.getMinutes()); // Current minutes
 
// getMonth()
console.log(date.getMonth()); // Current month (0-11)
 
// getSeconds()
console.log(date.getSeconds()); // Current seconds
 
// getTime()
console.log(date.getTime()); // Milliseconds since January 1, 1970
 
// getTimezoneOffset()
console.log(date.getTimezoneOffset()); // Timezone offset in minutes
 
// now()
console.log(Date.now()); // Current time in milliseconds since January 1, 1970
 
// parse()
console.log(Date.parse("2022-05-27")); // Milliseconds since January 1, 1970 for the given date
 
// setDate()
date.setDate(15);
console.log(date.getDate()); // 15
 
// setFullYear()
date.setFullYear(2022);
console.log(date.getFullYear()); // 2022
 
// setHours()
date.setHours(20);
console.log(date.getHours()); // 20
 
// setMinutes()
date.setMinutes(45);
console.log(date.getMinutes()); // 45
 
// setMonth()
date.setMonth(11);
console.log(date.getMonth()); // 11 (December)
 
// setSeconds()
date.setSeconds(30);
console.log(date.getSeconds()); // 30
 
// toDateString()
console.log(date.toDateString()); // "Wed Dec 15 2022" (example)
 
// toISOString()
console.log(date.toISOString()); // "2022-12-15T20:45:30.000Z" (example)
 
// toLocaleDateString()
console.log(date.toLocaleDateString()); // "12/15/2022" (example, depending on locale)
 
// toLocaleTimeString()
console.log(date.toLocaleTimeString()); // "8:45:30 PM" (example, depending on locale)
 
// toTimeString()
console.log(date.toTimeString()); // "20:45:30 GMT+0000 (UTC)" (example)
 
// toUTCString()
console.log(date.toUTCString()); // "Wed, 15 Dec 2022 20:45:30 GMT" (example)
 
// valueOf()
console.log(date.valueOf()); // Milliseconds since January 1, 1970
 
// setUTCDate() (ES2017)
date.setUTCDate(15);
console.log(date.getUTCDate()); // 15
 
// setUTCFullYear() (ES2017)
date.setUTCFullYear(2022);
console.log(date.getUTCFullYear()); // 2022
 
// setUTCHours() (ES2017)
date.setUTCHours(20);
console.log(date.getUTCHours()); // 20
 
// setUTCMinutes() (ES2017)
date.setUTCMinutes(45);
console.log(date.getUTCMinutes()); // 45
 
// setUTCMonth() (ES2017)
date.setUTCMonth(11);
console.log(date.getUTCMonth()); // 11 (December)
 
// setUTCSeconds() (ES2017)
date.setUTCSeconds(30);
console.log(date.getUTCSeconds()); // 30