Believemy

JavaScript glossary

Every word of JavaScript explained simply: keywords, built-in objects, methods, errors and concepts. Clear definitions and examples that actually run, to learn and to troubleshoot.
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ABCDEFGHIJ
K
LMNOPQRSTUVW
X
YZ

a

AbortController

Array.reduce()

Axios

await

async

Arrow function

Array.splice()

Array.sort()

Array.some()

Array.push()

addEventListener()

Array.map()

Array.forEach()

Array.flat()

Array.find()

Array.filter()

Array.every()

Array

arguments

b

Bundler

Boolean

break

Babel

c

createElement()

CORS

Cookie

continue

const

CommonJS

Coercion (type conversion)

Code coverage

Closure

classList

class

catch

Callback

Call stack

d

document

Destructuring

delete

Default parameter

default

dataset

Date

e

Event loop

extends

Express

export

Event propagation

Event delegation

ESLint

ES module

Error

else

f

false

fetch()

finally

for

FormData

function

g

getElementById()

Generic

h

Hoisting

i

includes()

IntersectionObserver

instanceof

indexOf()

innerHTML

in

import() (dynamic import)

import

Immutability

IIFE (immediately invoked function expression)

if

j

JSDoc

JSON

l

let

localStorage

Loose equality (==)

m

Mutation

Mock

Minification

Microtask

Math

Map

Memoization

n

npm

Number

Nullish coalescing (??)

null

npx

Node.js

Node.js

Next.js

new Promise

new

o

Object

of

Optional chaining (?.)

p

Promise.all()

Pure function

Prototype

Prototypal inheritance

Promise.race()

Promise

preventDefault()

Prettier

Polyfill

package.json

q

querySelector()

r

ReferenceError

return

RegExp

Rest (...)

Reference vs value

Recursion

React

RangeError

s

Strict equality (===)

SyntaxError

Symbol

switch

super

String.trim()

String.startsWith()

String.split()

String.replace()

String

slice()

static

Stack trace

Spread (...)

Source map

Side effect

setTimeout()

setInterval()

Set

sessionStorage

Scope

t

TypeScript

typeof

TypeError

try

Truthy and falsy

true

Tree shaking

Transpilation

throw

this binding

this

then()

textContent

Ternary operator (?:)

Template literal

u

Unit test

Union type

undefined

v

var

Vite

Vitest

w

Web Worker

Webpack

while

window

y

yield

z

Zod

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