JS Reference

JS by Category JS by Alphabet

JavaScript

JS Array JS Boolean

constructor prototype toString() valueOf()

constructor() extends static super

JS Date JS Error

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

parse() stringify()

JS Math JS Number

constructor isFinite() isInteger() isNaN() isSafeInteger() MAX_VALUE MIN_VALUE NEGATIVE_INFINITY NaN POSITIVE_INFINITY prototype toExponential() toFixed() toLocaleString() toPrecision() toString() valueOf()

JS Operators JS RegExp

Modifiers: g i m Groups: [abc] [^abc] [0-9] [^0-9] (x|y) Metacharacters: . \w \W \d \D \s \S \b \B \0 \n \f \r \t \v \xxx \xdd \uxxxx Quantifiers: + * ? {X} {X,Y} {X,} $ ^ ?= ?! Properties: constructor global ignoreCase lastIndex multiline source Methods: compile() exec() test() toString()

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

Window

Window Object Window Console

assert() clear() count() 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

DOM Document DOM Element

accessKey addEventListener() appendChild() attributes 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

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

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

DOM Event Objects

AnimationEvent ClipboardEvent DragEvent Event FocusEvent HashChangeEvent InputEvent KeyboardEvent MouseEvent PageTransitionEvent PopStateEvent ProgressEvent StorageEvent TouchEvent TransitionEvent UiEvent WheelEvent

DOM HTMLCollection

item() length namedItem()

alignContent alignItems alignSelf animation animationDelay animationDirection animationDuration animationFillMode animationIterationCount animationName animationTimingFunction animationPlayState background backgroundAttachment backgroundColor backgroundImage backgroundPosition backgroundRepeat backgroundClip backgroundOrigin 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 cursor direction display emptyCells filter flex flexBasis flexDirection flexFlow flexGrow flexShrink flexWrap cssFloat 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

Web APIs

API Console API Fullscreen

exitFullscreen() fullscreenElement fullscreenEnabled() requestFullscreen()

API Geolocation

coordinates position

API History API MediaQueryList API Storage

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

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()

JavaScript laat

❮ Vorige JavaScript -verklaringen Volgende ❯

Voorbeeld

Maak een variabele met de naam carName en wijs er de waarde "Volvo" aan toe:

let carName = "Volvo";

Hieronder meer voorbeelden.

Definitie en gebruik

De letverklaring declareert een variabele.

Variabelen zijn containers voor het opslaan van informatie.

Het maken van een variabele in JavaScript wordt een variabele "declareren" genoemd:

let carName;

Na de declaratie is de variabele leeg (hij heeft geen waarde).

Gebruik het gelijkteken om een waarde aan de variabele toe te kennen:

carName = "Volvo";

U kunt ook een waarde aan de variabele toewijzen wanneer u deze declareert:

let carName = "Volvo";

Opmerking

Een variabele gedeclareerd zonder waarde heeft de waarde undefined.

Zie ook:

JavaScript-referentie: JavaScript var

JavaScript-referentie: JavaScript-const

zelfstudies:

JavaScript-zelfstudie: JavaScript-variabelen

JavaScript-zelfstudie: JavaScript laat

JavaScript-zelfstudie: JavaScript-const

JavaScript-zelfstudie: JavaScript-bereik

Syntaxis

let name = value;

Parameters:

Parameter	Description
name	Required. The name of the variable. Variable names must follow these rules: Must begin with a letter, or $, or _ Names are case sensitive (y and Y are different) Reserved JavaScript words cannot be used as names
value	Optional. A value to be assigned to the variable.

Meer voorbeelden

Gebruik let om 5 toe te wijzen aan x en 6 aan y, en geef x + y weer:

let x = 5;
let y = 6;
document.getElementById("demo").innerHTML = x + y;

Declareer veel variabelen in één statement.

Begin de instructie met let en scheid de variabelen door een komma :

let lastName = "Doe",
age = 30,
job = "carpenter";

Gebruik laat in een lus:

let text = "";
for (let i = 0; i < 5; i++) {
text += i + "<br>";
}

Browserondersteuning

letis een ECMAScript6 (ES6)-functie.

ES6 (JavaScript 2015) wordt ondersteund in alle moderne browsers:


Chrome	Edge	Firefox	Safari	Opera
Yes	Yes	Yes	Yes	Yes

letwordt niet ondersteund in Internet Explorer 11 (of eerder).

❮ Vorige JavaScript -verklaringen Volgende ❯