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JavaScript

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Window

Window ObjectWindow ConsoleWindow HistoryWindow LocationWindow NavigatorWindow Screen

HTML DOM

HTML DocumentsHTML Elements
accessKeyaddEventListener()after()append()appendChild()attributesbefore()blur()childElementCountchildNodeschildrenclassListclassNameclick()clientHeightclientLeftclientTopclientWidthcloneNode()closest()compareDocumentPosition()contains()contentEditabledirfirstChildfirstElementChildfocus()getAttribute()getAttributeNode()getBoundingClientRect()getElementsByClassName()getElementsByTagName()hasAttribute()hasAttributes()hasChildNodes()idinnerHTMLinnerTextinsertAdjacentElement()insertAdjacentHTML()insertAdjacentText()insertBefore()isContentEditableisDefaultNamespace()isEqualNode()isSameNode()isSupported()langlastChildlastElementChildmatches()namespaceURInextSiblingnextElementSiblingnodeNamenodeTypenodeValuenormalize()offsetHeightoffsetWidthoffsetLeftoffsetParentoffsetTopouterHTMLouterTextownerDocumentparentNodeparentElementpreviousSiblingpreviousElementSiblingquerySelector()querySelectorAll()remove()removeAttribute()removeAttributeNode()removeChild()removeEventListener()replaceChild()scrollHeightscrollIntoView()scrollLeftscrollTopscrollWidthsetAttribute()setAttributeNode()styletabIndextagNametextContenttitle
HTML AttributesHTML CollectionHTML NodeListHTML DOMTokenListHTML Styles
alignContentalignItemsalignSelfanimationanimationDelayanimationDirectionanimationDurationanimationFillModeanimationIterationCountanimationNameanimationTimingFunctionanimationPlayStatebackgroundbackgroundAttachmentbackgroundClipbackgroundColorbackgroundImagebackgroundOriginbackgroundPositionbackgroundRepeatbackgroundSizebackfaceVisibilityborderborderBottomborderBottomColorborderBottomLeftRadiusborderBottomRightRadiusborderBottomStyleborderBottomWidthborderCollapseborderColorborderImageborderImageOutsetborderImageRepeatborderImageSliceborderImageSourceborderImageWidthborderLeftborderLeftColorborderLeftStyleborderLeftWidthborderRadiusborderRightborderRightColorborderRightStyleborderRightWidthborderSpacingborderStyleborderTopborderTopColorborderTopLeftRadiusborderTopRightRadiusborderTopStyleborderTopWidthborderWidthbottomboxShadowboxSizingcaptionSidecaretColorclearclipcolorcolumnCountcolumnFillcolumnGapcolumnRulecolumnRuleColorcolumnRuleStylecolumnRuleWidthcolumnscolumnSpancolumnWidthcounterIncrementcounterResetcssFloatcursordirectiondisplayemptyCellsfilterflexflexBasisflexDirectionflexFlowflexGrowflexShrinkflexWrapfontfontFamilyfontSizefontStylefontVariantfontWeightfontSizeAdjustheightisolationjustifyContentleftletterSpacinglineHeightlistStylelistStyleImagelistStylePositionlistStyleTypemarginmarginBottommarginLeftmarginRightmarginTopmaxHeightmaxWidthminHeightminWidthobjectFitobjectPositionopacityorderorphansoutlineoutlineColoroutlineOffsetoutlineStyleoutlineWidthoverflowoverflowXoverflowYpaddingpaddingBottompaddingLeftpaddingRightpaddingToppageBreakAfterpageBreakBeforepageBreakInsideperspectiveperspectiveOriginpositionquotesresizerightscrollBehaviortableLayouttabSizetextAligntextAlignLasttextDecorationtextDecorationColortextDecorationLinetextDecorationStyletextIndenttextOverflowtextShadowtextTransformtoptransformtransformOrigintransformStyletransitiontransitionPropertytransitionDurationtransitionTimingFunctiontransitionDelayunicodeBidiuserSelectverticalAlignvisibilitywidthwordBreakwordSpacingwordWrapwidowszIndex

HTML Events

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Web APIs

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HTML Objects

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Other References

CSSStyleDeclarationJS Conversion


Logical Nullish Assignment (??=)

Example

let x = null;
x ??= 10;
Try it Yourself »

Description

TheLogical Nullish Operator (??=) returns the right-side operand when the left-side operandis null or undefined. Otherwise it returns the left-side operand.

Browser Support

??= is a JavaScript 2020 feature.

ES 2020 is supported in all modern browsers sinceSeptember 2020:

Chrome
85		Edge
85		Firefox
79		Safari
14		Opera
71
Aug 2020Aug 2020Mar 2020Sep 2020Sep 2020
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