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JS Reference

JS by Category JS by Alphabet

JS Language

JS Primitive vs Object JS Object Hierarchy JS Error Hierarchy JS Iterables

JS Primitive Types

JS String JS Number JS Boolean JS BigInt JS Symbol JS undefined JS null JS undefined vs null

JS Constructors

Array() BigInt() Boolean() Date() Error() Function() Map() Number() Object() Promise() RegExp() Set() String() Symbol() WeakMap() WeakSet()

JS Operators JS Assignment

Assign Simple Assign Add Assign Subtract Assign Multiply Assign Divide Assign Remainder Assign Colon Assign AND Assign OR Assign Nullish

Addition Subtraction Multiplication Division Exponentiation Remainder Increment Decrement Concatenation Unary Plus Unary Negation

Equal Strict Equal Not Equal Strict Not Equal Greater Than Less Than Greater Equal Less Equal

JS Logical Operators

Logical AND Logical OR Logical NOT Logical Nullish

JS Bitwise Operators

Bitwise AND Bitwise OR Bitwise NOT Bitwise XOR Bitwise Left Bitwise Right Bitwise Signed

JS Misc Operators

: Colon . Dot [ ] Bracket [ ] Array Literal { } Block { } Object Literal ?. Chaining ... Spread ( ) Grouping ( ) ? x : y Ternary ( ) Invocation => Arrow delete in instanceof typeof void yield yield*

JS Objects

Array[ ] Array( ) at() concat() constructor copyWithin() entries() every() fill() filter() find() findIndex() findLast() findLastIndex() flat() flatMap() forEach() from() includes() indexOf() isArray() join() keys() lastIndexOf() length map() of() pop() prototype push() reduce() reduceRight() rest (...) reverse() shift() slice() some() sort() splice() spread (...) toReversed() toSorted() toSpliced() toString() unshift() values() valueOf() with()

toString() valueOf()

Boolean() new Boolean() constructor prototype toString() valueOf()

constructor() extends static super

new Date() constructor getDate() getDay() getFullYear() getHours() getMilliseconds() getMinutes() getMonth() getSeconds() getTime() getTimezoneOffset() getUTCDate() getUTCDay() getUTCFullYear() getUTCHours() getUTCMilliseconds() getUTCMinutes() getUTCMonth() getUTCSeconds() now() parse() prototype setDate() setFullYear() setHours() setMilliseconds() setMinutes() setMonth() setSeconds() setTime() setUTCDate() setUTCFullYear() setUTCHours() setUTCMilliseconds() setUTCMinutes() setUTCMonth() setUTCSeconds() toDateString() toISOString() toJSON() toLocaleDateString() toLocaleTimeString() toLocaleString() toString() toTimeString() toUTCString() UTC() valueOf()

Function apply() Function bind() Function call() Function length Function name Function toString() Function valueOf()

new Error() cause isError() name message

decodeURI() decodeURIComponent() encodeURI() encodeURIComponent() escape() eval() Infinity isFinite() isNaN() NaN Number() parseFloat() parseInt() String() undefined unescape()

JS Intl Namespace JS Iterators

drop() every() filter() find() flatMap() forEach() from() map() reduce() some() take()

parse() stringify()

new Map() clear() delete() entries() forEach() get() groupBy() has() keys() set() size values()

abs() acos() acosh() asin() asinh() atan() atan2() atanh() cbrt() ceil() clz32() cos() cosh() E exp() expm1() f16round() floor() fround() LN2 LN10 log() log10() log1p() log2() LOG2E LOG10E max() min() PI pow() random() round() sign() sin() sinh() sqrt() SQRT1_2 SQRT2 tan() tanh() trunc()

constructor EPSILON isFinite() isInteger() isNaN() isSafeInteger() MAX_SAFE_INTEGER MIN_SAFE_INTEGER MAX_VALUE MIN_VALUE NaN NEGATIVE_INFINITY POSITIVE_INFINITY parseFloat() parseInt() prototype toExponential() toFixed() toLocaleString() toPrecision() toString() valueOf()

assign() constructor create() defineProperties() defineProperty() delete entries() freeze() fromEntries() getOwnPropertyDescriptor() getOwnPropertyDescriptors() getOwnPropertyNames() groupBy() isExtensible() isFrozen() isSealed() keys() preventExtensions() prototype seal() toString() valueOf() values()

all() allSettled() any() catch() finally() race() reject() resolve() then() try() withResolvers()

apply() construct() defineProperty() deleteProperty() get() getOwnPropertyDescriptor() getPrototypeOf() has() isExtensible() ownKeys() preventExtensions() set() setPrototypeOf()

apply() construct() defineProperty() deleteProperty() get() getOwnPropertyDescriptor() getPrototypeOf() has() isExtensible() ownKeys() preventExtensions() set() setPrototypeOf()

JS RegExp Patterns

/d /g /i /m /s /u /v /y [a] [^a] [abc] [^abc] [A-Z] [^A-Z] [0-9] [^0-9] a|b . \w \W \d \D \s \S [\b] 0円 \n \f \r \t \v \p \P \ddd \xhh \uhhhh ^ $ \b \B x(?=y) x(?!y) (?<=y)x (?<!y)x (x) (?<name>x) (?flags:x) + * ? {n} {n,m} {n,}

JS RegExp Reference

compile() constructor dotAll escape() exec() flags global hasIndices ignoreCase lastIndex multiline source sticky test() toString() unicode unicodeSets

new Set() add() clear() delete() difference() entries() forEach() has() intersection() isDisjointFrom() isSubsetOf() isSupersetOf() keys() size symmetricDifference() union() values()

break class const continue debugger do...while for for...in for...of function if...else let return switch throw try...catch var while

at() charAt() charCodeAt() codePointAt() concat() constructor endsWith() fromCharCode() includes() indexOf() isWellFormed() lastIndexOf() length localeCompare() match() matchAll() padEnd() padStart() prototype repeat() replace() replaceAll() search() slice() split() startsWith() substr() substring() toLocaleLowerCase() toLocaleUpperCase() toLowerCase() toString() toUpperCase() toWellFormed() trim() trimEnd() trimStart() valueOf()

JS Typed Arrays

Int8Array Uint8Array Uint8ClampedArray Int16Array Uint16Array Int32Array Uint32Array BigInt64Array BigUint64Array Float16Array Float32Array Float64Array

JS Typed Reference

at() byteLength byteOffset bytesPerElement copyWithin() entries() every() fill() filter() find() findIndex() findLast() findLastIndex() forEach() from() includes() indexOf() join() keys() lastIndexOf() length map() name of() reduce() reduceRight() reverse() set() slice() some() sort() subarray() toLocaleString() toReversed() toSorted() toString() values() with()

Temporal

All (Reference) New Duration

abs() add() compare() from() negated() new (constructor) round() subtract() toJSON() toLocaleString() toString() total() valueOf() with()

add() compare() equals() from() fromEpochMilliseconds() fromEpochNanoseconds() new (constructor) round() since() subtract() toJSON() toLocaleString() toString() toZonedDateTimeISO() until() valueOf()

instant() plainDateISO() plainDateTimeISO() plainTimeISO() timeZoneId() zonedDateTimeISO()

add() compare() equals() from() new (constructor) since() subtract() toJSON() toLocaleString() toPlainDateTime() toPlainMonthDay() toPlainYearMonth() toString() toZonedDateTime() until() valueOf() with() withCalendar()

add() compare() equals() from() new (constructor) round() since() subtract() toJSON() toLocaleString() toPlainDate() toPlainTime() toString() toZonedDateTime() until() valueOf() with() withCalendar() withPlainTime()

equals() from() new (constructor) toJSON() toLocaleString() toPlainDate() toString() valueOf() with()

add() compare() equals() from() new (constructor) round() since() subtract() toJSON() toLocaleString() toString() until() valueOf() with()

add() compare() equals() from() new (constructor) since() subtract() toJSON() toLocaleString() toPlaindate() toString() until() valueOf() with()

add() compare() equals() from() getTimeZonetransition() new() round() since() startofday() subtract() toInstant() toJSON() toLocaleString() toPlainDate() toPlainDateTime() toPlainTime() toString() until() valueOf() with() withCalendar() withPlainTime() withTimeZone()

Window

addEventlistener() alert() atob() blur() btoa() clearInterval() clearTimeout() close() closed confirm() console defaultStatus document focus() frameElement frames history getComputedStyle() innerHeight innerWidth length localStorage location matchMedia() moveBy() moveTo() name navigator open() opener outerHeight outerWidth pageXOffset pageYOffset parent print() prompt() removeEventlistener() resizeBy() resizeTo() screen screenLeft screenTop screenX screenY scrollBy() scrollTo() scrollX scrollY sessionStorage self setInterval() setTimeout() status stop() top

assert() clear() count() dir() error() group() groupCollapsed() groupEnd() info() log() table() time() timeEnd() trace() warn()

back() forward() go() length

Window Location

assign() hash host hostname href origin pathname port protocol reload() replace() search

Window Navigator

appCodeName appName appVersion cookieEnabled geolocation javaEnabled() language onLine platform product taintEnabled() userAgent

availHeight availWidth colorDepth height pixelDepth width

HTML DOM

activeElement addEventListener() adoptNode() anchors applets baseURI body charset characterSet close() cookie createAttribute() createComment() createDocumentFragment() createElement() createEvent() createTextNode() defaultView designMode doctype documentElement documentMode documentURI domain domConfig embeds execCommand() forms getElementById() getElementsByClassName() getElementsByName() getElementsByTagName() hasFocus() head images implementation importNode() inputEncoding lastModified links normalize() normalizeDocument() open() querySelector() querySelectorAll() readyState referrer removeEventListener() renameNode() scripts strictErrorChecking title URL write() writeln()

accessKey addEventListener() after() append() appendChild() attributes before() blur() childElementCount childNodes children classList className click() clientHeight clientLeft clientTop clientWidth cloneNode() closest() compareDocumentPosition() contains() contentEditable dir firstChild firstElementChild focus() getAttribute() getAttributeNode() getBoundingClientRect() getElementsByClassName() getElementsByTagName() hasAttribute() hasAttributes() hasChildNodes() id innerHTML innerText insertAdjacentElement() insertAdjacentHTML() insertAdjacentText() insertBefore() isContentEditable isDefaultNamespace() isEqualNode() isSameNode() isSupported() lang lastChild lastElementChild matches() namespaceURI nextSibling nextElementSibling nodeName nodeType nodeValue normalize() offsetHeight offsetWidth offsetLeft offsetParent offsetTop outerHTML outerText ownerDocument parentNode parentElement previousSibling previousElementSibling querySelector() querySelectorAll() remove() removeAttribute() removeAttributeNode() removeChild() removeEventListener() replaceChild() scrollHeight scrollIntoView() scrollLeft scrollTop scrollWidth setAttribute() setAttributeNode() style tabIndex tagName textContent title

HTML Attributes

getNamedItem() isId item() length name removeNamedItem() setNamedItem() specified value

HTML Collection

item() length namedItem()

entries() forEach() item() keys() length values()

HTML DOMTokenList

add() contains() entries() forEach() item() keys() length remove() replace() supports() toggle() value values()

alignContent alignItems alignSelf animation animationDelay animationDirection animationDuration animationFillMode animationIterationCount animationName animationTimingFunction animationPlayState background backgroundAttachment backgroundClip backgroundColor backgroundImage backgroundOrigin backgroundPosition backgroundRepeat backgroundSize backfaceVisibility border borderBottom borderBottomColor borderBottomLeftRadius borderBottomRightRadius borderBottomStyle borderBottomWidth borderCollapse borderColor borderImage borderImageOutset borderImageRepeat borderImageSlice borderImageSource borderImageWidth borderLeft borderLeftColor borderLeftStyle borderLeftWidth borderRadius borderRight borderRightColor borderRightStyle borderRightWidth borderSpacing borderStyle borderTop borderTopColor borderTopLeftRadius borderTopRightRadius borderTopStyle borderTopWidth borderWidth bottom boxShadow boxSizing captionSide caretColor clear clip color columnCount columnFill columnGap columnRule columnRuleColor columnRuleStyle columnRuleWidth columns columnSpan columnWidth counterIncrement counterReset cssFloat cursor direction display emptyCells filter flex flexBasis flexDirection flexFlow flexGrow flexShrink flexWrap font fontFamily fontSize fontStyle fontVariant fontWeight fontSizeAdjust height isolation justifyContent left letterSpacing lineHeight listStyle listStyleImage listStylePosition listStyleType margin marginBottom marginLeft marginRight marginTop maxHeight maxWidth minHeight minWidth objectFit objectPosition opacity order orphans outline outlineColor outlineOffset outlineStyle outlineWidth overflow overflowX overflowY padding paddingBottom paddingLeft paddingRight paddingTop pageBreakAfter pageBreakBefore pageBreakInside perspective perspectiveOrigin position quotes resize right scrollBehavior tableLayout tabSize textAlign textAlignLast textDecoration textDecorationColor textDecorationLine textDecorationStyle textIndent textOverflow textShadow textTransform top transform transformOrigin transformStyle transition transitionProperty transitionDuration transitionTimingFunction transitionDelay unicodeBidi userSelect verticalAlign visibility width wordBreak wordSpacing wordWrap widows zIndex

HTML Events

abort afterprint animationend animationiteration animationstart beforeprint beforeunload blur canplay canplaythrough change click contextmenu copy cut dblclick drag dragend dragenter dragleave dragover dragstart drop durationchange ended error focus focusin focusout fullscreenchange fullscreenerror hashchange input invalid keydown keypress keyup load loadeddata loadedmetadata loadstart message mousedown mouseenter mouseleave mousemove mouseover mouseout mouseup offline online open pagehide pageshow paste pause play playing progress ratechange resize reset scroll search seeked seeking select show stalled submit suspend timeupdate toggle touchcancel touchend touchmove touchstart transitionend unload volumechange waiting wheel

HTML Event Objects

Animation Events Clipboard Events Drag Events Events Focus Events HashChange Events Input Events Keyboard Events Mouse Events PageTransition Events PopState Events Progress Events Storage Events Touch Events Transition Events Ui Events Wheel Events

HTML Event Properties

altKey (Mouse) altKey (Key) animationName bubbles button buttons cancelable charCode clientX clientY code ctrlKey (Mouse) ctrlKey (Key) currentTarget data defaultPrevented deltaX deltaY deltaZ deltaMode detail elapsedTime elapsedTime eventPhase inputType isTrusted key keyCode location metaKey (Mouse) metaKey (Key) newURL oldURL offsetX offsetY pageX pageY persisted propertyName relatedTarget relatedTarget screenX screenY shiftKey (Mouse) shiftKey (Key) target targetTouches timeStamp touches type which (Mouse) which (Key) view

HTML Event Methods

getModifierState() preventDefault() stopImmidiatePropagation() stopPropagation()

Web APIs

API Canvas API Console API Fetch API Fullscreen

exitFullscreen() fullscreenElement fullscreenEnabled() requestFullscreen()

API Geolocation

coordinates getCurrentPosition() position

API History API MediaQueryList API Storage

clear() getItem() key() length removeItem() setItem()

API Validation API Web

crypto.getRandomNumber()

HTML Objects

<a> <abbr> <address> <area> <article> <aside> <audio> <b> <base> <bdo> <blockquote> <body> <br> <button> <canvas> <caption> <cite> <code> <col> <colgroup> <datalist> <dd> <del> <details> <dfn> <dialog> <div> <dl> <dt> <em> <embed> <fieldset> <figcaption> <figure> <footer> <form> <head> <header> <h1> - <h6> <hr> <html> <i> <iframe> <img> <ins> <input> button <input> checkbox <input> color <input> date <input> datetime <input> datetime-local <input> email <input> file <input> hidden <input> image <input> month <input> number <input> password <input> radio <input> range <input> reset <input> search <input> submit <input> text <input> time <input> url <input> week <kbd> <label> <legend> <li> <link> <map> <mark> <menu> <menuitem> <meta> <meter> <nav> <object> <ol> <optgroup> <option> <output> <p> <param> <pre> <progress> <q> <s> <samp> <script> <section> <select> <small> <source> <span> <strong> <style> <sub> <summary> <sup> <table> <tbody> <td> <tfoot> <th> <thead> <tr> <textarea> <time> <title> <track> <u> <ul> <var> <video>

Other References

CSSStyleDeclaration

cssText getPropertyPriority() getPropertyValue() item() length parentRule removeProperty() setProperty()

PlainDateTime add()

❮ Previous PlainDateTime Reference Next ❯

Example

const date1 = Temporal.PlainDateTime.from("2026-05-17T14:30:00");

const date2 = date1.add({ months:1, days:10 });

Try it Yourself »

Description

The add() method returns a new Temporal.PlainDateTime object with a duration added.

The add() method does not change the original PlainDateTime.

Syntax

plaindatetime.add(duration)

Parameters

Parameter Description

duration The duration to be added.

Return Value

Type Description

Object A new PlainDateTime object with the duration added.

Browser Support

Temporal is a major update to the JavaScript standard (TC39).

It is currently supported in Chrome, Edge, Firefox, and Opera and is expected to reach full availability across browsers before the summer of 2026.

Chrome 144	Edge 144	Firefox 139	Safari	Opera 128
Jan 2026	Jan 2026	May 2025	🚫	Feb 2026

The Safari implementation can be tested in Safari Technology Preview by enabling the --use-temporal runtime flag.

Polyfill

Until Safari supports Temporal natively, you can use the official polyfill:

<script
src="https://cdn.jsdelivr.net/npm/@js-temporal/polyfill/dist/index.umd.js">
</script>

❮ Previous PlainDateTime Reference Next ❯

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