JS Objects Reference
JavaScript's built-in objects, grouped by category. Each one has its own deep page on MDN — this is the lookup index.
Primitives & wrappers
| Type | Notable members |
|---|---|
String | length, slice, split, replace, includes, startsWith, padStart, match |
Number | toFixed, toString, Number.isFinite, Number.isNaN, Number.MAX_SAFE_INTEGER |
BigInt | toString(radix), integer arithmetic without precision loss |
Boolean | Boolean(x), !!x |
Symbol | Symbol("desc"), Symbol.iterator, well-known symbols |
Collections
| Type | Notable members |
|---|---|
Array | map, filter, reduce, find, slice, splice, sort, flat, toSorted, at |
Object | keys, values, entries, assign, freeze, create, hasOwn |
Map | get, set, has, delete, size |
Set | add, has, delete, size, union, intersection |
WeakMap / WeakSet | Key/values without preventing garbage collection |
| Typed arrays | Uint8Array, Int32Array, Float64Array, … |
Functions & classes
| Type | Notable members |
|---|---|
Function | call, apply, bind, length, name |
Promise | then, catch, finally, Promise.all, any, race, allSettled |
Date | now, getTime, toISOString, getters/setters |
RegExp | test, exec, flags, named captures |
Error + subclasses | TypeError, RangeError, SyntaxError, ReferenceError, URIError, AggregateError |
Math / JSON / Intl / global
| Object | What it does |
|---|---|
Math | Constants (PI), abs, round, min, max, random, trig, log |
JSON | parse, stringify |
Intl | NumberFormat, DateTimeFormat, Collator, ListFormat, PluralRules |
globalThis | Universal global reference |
Reflect | Functional reflection — Reflect.get, set, has, apply, construct |
Proxy | Intercept operations on an object |
Tip: Open the browser DevTools console and type
Array.prototype. — autocomplete is a free reference. Same for Object., Math., String.prototype..Example
Example
<!DOCTYPE html>
<html>
<body>
<p id="out"></p>
<script>
document.getElementById("out").textContent = "Hello from JS Objects Reference!";
</script>
</body>
</html>
Try it Yourself »
Exercise
The non-mutating sort method added in ES2023 is…
const next = arr.
();
Eight letters, camelCase.
Discussion
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