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JS Reference

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JavaScript

JS Array
concat() constructor copyWithin() entries() every() fill() filter() find() findIndex() forEach() from() includes() indexOf() isArray() join() keys() lastIndexOf() length map() pop() prototype push() reduce() reduceRight() reverse() shift() slice() some() sort() splice() toString() unshift() valueOf()
JS Boolean
constructor prototype toString() valueOf()
JS Classes
constructor() extends static super
JS 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()
JS Error
name message
JS Global
decodeURI() decodeURIComponent() encodeURI() encodeURIComponent() escape() eval() Infinity isFinite() isNaN() NaN Number() parseFloat() parseInt() String() undefined unescape()
JS JSON
parse() stringify()
JS Math
abs() acos() acosh() asin() asinh() atan() atan2() atanh() cbrt() ceil() clz32() cos() cosh() E exp() expm1() 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()
JS Number
constructor isFinite() isInteger() isNaN() isSafeInteger() MAX_VALUE MIN_VALUE NEGATIVE_INFINITY NaN POSITIVE_INFINITY prototype toExponential() toFixed() toLocaleString() toPrecision() toString() valueOf()
JS Object
constructor keys() prototype 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()
JS Statements
break class const continue debugger do...while for for...in for...of function if...else let return switch throw try...catch var while
JS String
charAt() charCodeAt() codePointAt() concat() constructor endsWith() fromCharCode() includes() indexOf() lastIndexOf() length localeCompare() match() prototype repeat() replace() search() slice() split() startsWith() substr() substring() toLocaleLowerCase() toLocaleUpperCase() toLowerCase() toString() toUpperCase() trim() trimEnd() trimStart() valueOf()
JS TypedArray

Window

Window Object
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() resizeBy() resizeTo() screen screenLeft screenTop screenX screenY scrollBy() scrollTo() scrollX scrollY sessionStorage self setInterval() setTimeout() status stop() top
Window Console
assert() clear() count() error() group() groupCollapsed() groupEnd() info() log() table() time() timeEnd() trace() warn()
Window History
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
Window Screen
availHeight availWidth colorDepth height pixelDepth width

HTML DOM

HTML Documents
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()
HTML Elements
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
HTML Attributes
getNamedItem() isId item() length name removeNamedItem() setNamedItem() specified value
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 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
HTML Event Objects
AnimationEvent ClipboardEvent DragEvent Event FocusEvent HashChangeEvent InputEvent KeyboardEvent MouseEvent PageTransitionEvent PopStateEvent ProgressEvent StorageEvent TouchEvent TransitionEvent UiEvent WheelEvent
HTML Collection
item() length namedItem()
HTML NodeList
entries() forEach() item() keys() length values()
HTML DOMTokenList
add() contains() entries() forEach() item() keys() length remove() replace() supports() toggle() value values()
HTML Styles
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 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

Web APIs

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()
JS Conversion


Style opacity Property

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Example

Make a DIV element transparent:

document.getElementById("myDIV").style.opacity = "0.5";
Try it Yourself »

Definition and Usage

The opacity property sets or returns the opacity level of an element.

The opacity-level of an element describes the transparency-level, where 1 is not transperant at all, 0.5 is 50% see-through, and 0 is completely transparent.

Browser Support

Property
opacity Yes Yes Yes Yes Yes

Syntax

Return the opacity property:

object.style.opacity

Set the opacity property:

object.style.opacity = "number|initial|inherit"

Property Values

Value Description
number Specifies the opacity. From 0.0 (fully transparent) to 1.0 (fully opaque)
initial Sets this property to its default value. Read about initial
inherit Inherits this property from its parent element. Read about inherit

Technical Details

Default Value: 1
Return Value: A String, representing the opacity-level of an element
CSS Version CSS3

Related Pages

CSS reference: opacity property


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