JavaScript標識符不可用

Question

我剛剛發現命名變量arguments的難題是一個壞主意。

var arguments = 5; 

(function() { 
    console.log(arguments); 
})(); 

Output: []

事實證明，arguments是"a local variable available within all functions"所以在每一個新的執行上下文，arguments被遮蔽。

我的問題是：是否還有其他如arguments這樣的背信名稱，不是真的reserved words，但會造成問題？

Answer 1

有內部功能沒有其他自動符號（除this，但你不能無論如何創建該名稱的變量），如果這就是你的意思。但是有幾個默認的全局變量，所以在函數內定義一個具有相同名稱的變量將會影響全局變量。

Answer 2

是的。例如，與window或document類似。查看更長的列表here（「其他javascript關鍵字」）。

不推薦使用它們中的任何一個，即使有些按預期工作。

編輯：正如javascript.about.com中提到的，「雖然它們不是保留字，但應避免使用這些字作爲變量和函數。」他們列出的主要內容與歸類爲predefined classes and objects和global properties的歸類相同。一個問題的

實施例：

var window = 5; 

(function() { 
    alert(window); 
})(); 

上面的代碼具有不可預知的結果，由於事實是window指窗口對象的單詞。 Firefox會阻止對它進行修改，因此警報仍然會引用窗口對象，而在IE8中，您將獲得值爲5的警報。

Answer 3

您可以通過控制檯執行該得到的全局命名空間中使用的所有名稱的列表：

var t = []; 
for(v in this){t.push(v)} 
console.log(t.sort()); 

結果：

["$","ArrayBuffer","Attr","Audio","AudioProcessingEvent","BeforeLoadEvent","Blob","CDATASection","CSSCharsetRule","CSSFontFaceRule","CSSImportRule","CSSMediaRule","CSSPageRule","CSSPrimitiveValue","CSSRule","CSSRuleList","CSSStyleDeclaration","CSSStyleRule","CSSStyleSheet","CSSValue","CSSValueList","CTIsPlayback","CanvasGradient","CanvasPattern","CanvasRenderingContext2D","CharacterData","ClientRect","ClientRectList","Clipboard","CloseEvent","Comment","CompositionEvent","Counter","CustomEvent","DOMException","DOMImplementation","DOMParser","DOMSettableTokenList","DOMStringList","DOMStringMap","DOMTokenList","DataView","DeviceOrientationEvent","Document","DocumentFragment","DocumentType","Element","Entity","EntityReference","ErrorEvent","Event","EventEmitter","EventException","EventSource","File","FileError","FileList","FileReader","Float32Array","Float64Array","FormData","Generator","HTMLAllCollection","HTMLAnchorElement","HTMLAppletElement","HTMLAreaElement","HTMLAudioElement","HTMLBRElement","HTMLBaseElement","HTMLBaseFontElement","HTMLBodyElement","HTMLButtonElement","HTMLCanvasElement","HTMLCollection","HTMLDListElement","HTMLDataListElement","HTMLDirectoryElement","HTMLDivElement","HTMLDocument","HTMLElement","HTMLEmbedElement","HTMLFieldSetElement","HTMLFontElement","HTMLFormElement","HTMLFrameElement","HTMLFrameSetElement","HTMLHRElement","HTMLHeadElement","HTMLHeadingElement","HTMLHtmlElement","HTMLIFrameElement","HTMLImageElement","HTMLInputElement","HTMLKeygenElement","HTMLLIElement","HTMLLabelElement","HTMLLegendElement","HTMLLinkElement","HTMLMapElement","HTMLMarqueeElement","HTMLMediaElement","HTMLMenuElement","HTMLMetaElement","HTMLMeterElement","HTMLModElement","HTMLOListElement","HTMLObjectElement","HTMLOptGroupElement","HTMLOptionElement","HTMLOutputElement","HTMLParagraphElement","HTMLParamElement","HTMLPreElement","HTMLProgressElement","HTMLQuoteElement","HTMLScriptElement","HTMLSelectElement","HTMLSourceElement","HTMLSpanElement","HTMLStyleElement","HTMLTableCaptionElement","HTMLTableCellElement","HTMLTableColElement","HTMLTableElement","HTMLTableRowElement","HTMLTableSectionElement","HTMLTextAreaElement","HTMLTitleElement","HTMLTrackElement","HTMLUListElement","HTMLUnknownElement","HTMLVideoElement","HashChangeEvent","IceCandidate","Image","ImageData","Int16Array","Int32Array","Int8Array","KeyboardEvent","Markdown","MediaController","MediaError","MediaList","MediaStreamEvent","MessageChannel","MessageEvent","MessagePort","MimeType","MimeTypeArray","MouseEvent","MutationEvent","NamedNodeMap","Node","NodeFilter","NodeList","Notation","Notification","OfflineAudioCompletionEvent","Option","OverflowEvent","PERSISTENT","PR","PR_SHOULD_USE_CONTINUATION","PageTransitionEvent","Plugin","PluginArray","PopStateEvent","ProcessingInstruction","ProgressEvent","RGBColor","RTCIceCandidate","RTCSessionDescription","Range","RangeException","Rect","SQLException","SVGAElement","SVGAltGlyphDefElement","SVGAltGlyphElement","SVGAltGlyphItemElement","SVGAngle","SVGAnimateColorElement","SVGAnimateElement","SVGAnimateMotionElement","SVGAnimateTransformElement","SVGAnimatedAngle","SVGAnimatedBoolean","SVGAnimatedEnumeration","SVGAnimatedInteger","SVGAnimatedLength","SVGAnimatedLengthList","SVGAnimatedNumber","SVGAnimatedNumberList","SVGAnimatedPreserveAspectRatio","SVGAnimatedRect","SVGAnimatedString","SVGAnimatedTransformList","SVGCircleElement","SVGClipPathElement","SVGColor","SVGComponentTransferFunctionElement","SVGCursorElement","SVGDefsElement","SVGDescElement","SVGDocument","SVGElement","SVGElementInstance","SVGElementInstanceList","SVGEllipseElement","SVGException","SVGFEBlendElement","SVGFEColorMatrixElement","SVGFEComponentTransferElement","SVGFECompositeElement","SVGFEConvolveMatrixElement","SVGFEDiffuseLightingElement","SVGFEDisplacementMapElement","SVGFEDistantLightElement","SVGFEDropShadowElement","SVGFEFloodElement","SVGFEFuncAElement","SVGFEFuncBElement","SVGFEFuncGElement","SVGFEFuncRElement","SVGFEGaussianBlurElement","SVGFEImageElement","SVGFEMergeElement","SVGFEMergeNodeElement","SVGFEMorphologyElement","SVGFEOffsetElement","SVGFEPointLightElement","SVGFESpecularLightingElement","SVGFESpotLightElement","SVGFETileElement","SVGFETurbulenceElement","SVGFilterElement","SVGFontElement","SVGFontFaceElement","SVGFontFaceFormatElement","SVGFontFaceNameElement","SVGFontFaceSrcElement","SVGFontFaceUriElement","SVGForeignObjectElement","SVGGElement","SVGGlyphElement","SVGGlyphRefElement","SVGGradientElement","SVGHKernElement","SVGImageElement","SVGLength","SVGLengthList","SVGLineElement","SVGLinearGradientElement","SVGMPathElement","SVGMarkerElement","SVGMaskElement","SVGMatrix","SVGMetadataElement","SVGMissingGlyphElement","SVGNumber","SVGNumberList","SVGPaint","SVGPathElement","SVGPathSeg","SVGPathSegArcAbs","SVGPathSegArcRel","SVGPathSegClosePath","SVGPathSegCurvetoCubicAbs","SVGPathSegCurvetoCubicRel","SVGPathSegCurvetoCubicSmoothAbs","SVGPathSegCurvetoCubicSmoothRel","SVGPathSegCurvetoQuadraticAbs","SVGPathSegCurvetoQuadraticRel","SVGPathSegCurvetoQuadraticSmoothAbs","SVGPathSegCurvetoQuadraticSmoothRel","SVGPathSegLinetoAbs","SVGPathSegLinetoHorizontalAbs","SVGPathSegLinetoHorizontalRel","SVGPathSegLinetoRel","SVGPathSegLinetoVerticalAbs","SVGPathSegLinetoVerticalRel","SVGPathSegList","SVGPathSegMovetoAbs","SVGPathSegMovetoRel","SVGPatternElement","SVGPoint","SVGPointList","SVGPolygonElement","SVGPolylineElement","SVGPreserveAspectRatio","SVGRadialGradientElement","SVGRect","SVGRectElement","SVGRenderingIntent","SVGSVGElement","SVGScriptElement","SVGSetElement","SVGStopElement","SVGStringList","SVGStyleElement","SVGSwitchElement","SVGSymbolElement","SVGTRefElement","SVGTSpanElement","SVGTextContentElement","SVGTextElement","SVGTextPathElement","SVGTextPositioningElement","SVGTitleElement","SVGTransform","SVGTransformList","SVGUnitTypes","SVGUseElement","SVGVKernElement","SVGViewElement","SVGViewSpec","SVGZoomAndPan","SVGZoomEvent","Selection","SessionDescription","SharedWorker","SpeechInputEvent","StackExchange","Storage","StorageEvent","StyleSheet","StyleSheetList","TEMPORARY","Text","TextEvent","TextMetrics","TextTrack","TextTrackCue","TextTrackCueList","TextTrackList","TimeRanges","TouchEvent","TrackEvent","UIEvent","URL","Uint16Array","Uint32Array","Uint8Array","Uint8ClampedArray","WebGLActiveInfo","WebGLBuffer","WebGLContextEvent","WebGLFramebuffer","WebGLProgram","WebGLRenderbuffer","WebGLRenderingContext","WebGLShader","WebGLShaderPrecisionFormat","WebGLTexture","WebGLUniformLocation","WebKitAnimationEvent","WebKitBlobBuilder","WebKitCSSFilterValue","WebKitCSSKeyframeRule","WebKitCSSKeyframesRule","WebKitCSSMatrix","WebKitCSSRegionRule","WebKitCSSTransformValue","WebKitIntent","WebKitMediaSource","WebKitMutationObserver","WebKitPoint","WebKitSourceBuffer","WebKitSourceBufferList","WebKitTransitionEvent","WebSocket","WheelEvent","Window","WinterBash","Worker","XMLDocument","XMLHttpRequest","XMLHttpRequestException","XMLHttpRequestProgressEvent","XMLHttpRequestUpload","XMLSerializer","XPathEvaluator","XPathException","XPathResult","XSLTProcessor","__qc","_gaq","_gat","_qevents","addEventListener","alert","apiCallbacks","applicationCache","atob","blur","btoa","captureEvents","careers_adselector","careers_adurl","careers_companycssurl","careers_cssurl","careers_leaderboardcssurl","chrome","clearInterval","clearTimeout","clientInformation","close","closed","confirm","console","crypto","defaultStatus","defaultstatus","devicePixelRatio","dispatchEvent","document","event","external","find","focus","frameElement","frames","gaGlobal","gauth","genuwine","getComputedStyle","getMatchedCSSRules","getSelection","history","i","initFadingHelpText","initTagRenderer","innerHeight","innerWidth","jQuery","jQuery171005593172716908157_1357215797040","jQuery171005593172716908157_1357215797041","length","localStorage","location","locationbar","matchMedia","menubar","moveBy","moveScroller","moveTo","name","navigator","offscreenBuffering","onabort","onbeforeunload","onblur","oncanplay","oncanplaythrough","onchange","onclick","oncontextmenu","ondblclick","ondeviceorientation","ondrag","ondragend","ondragenter","ondragleave","ondragover","ondragstart","ondrop","ondurationchange","onemptied","onended","onerror","onfocus","onhashchange","oninput","oninvalid","onkeydown","onkeypress","onkeyup","onload","onloadeddata","onloadedmetadata","onloadstart","onmessage","onmousedown","onmousemove","onmouseout","onmouseover","onmouseup","onmousewheel","onoffline","ononline","onpagehide","onpageshow","onpause","onplay","onplaying","onpopstate","onprogress","onratechange","onreset","onresize","onscroll","onsearch","onseeked","onseeking","onselect","onstalled","onstorage","onsubmit","onsuspend","ontimeupdate","onunload","onvolumechange","onwaiting","onwebkitanimationend","onwebkitanimationiteration","onwebkitanimationstart","onwebkittransitionend","open","openDatabase","opener","outerHeight","outerWidth","pageXOffset","pageYOffset","parent","performance","personalbar","postMessage","prepareEditor","prettyPrint","prettyPrintOne","print","profileLink","prompt","quantserve","releaseEvents","removeEventListener","resizeBy","resizeTo","sanitizeAndSplitTags","screen","screenLeft","screenTop","screenX","screenY","scriptSrc","scroll","scrollBy","scrollTo","scrollX","scrollY","scrollbars","self","sessionStorage","setInterval","setTimeout","showFadingHelpText","showModalDialog","status","statusbar","stop","styleCode","styleMedia","t","tagRenderer","tagRendererRaw","toolbar","top","uh","v","v8Intl","votesCast","webkitAudioContext","webkitAudioPannerNode","webkitCancelAnimationFrame","webkitCancelRequestAnimationFrame","webkitConvertPointFromNodeToPage","webkitConvertPointFromPageToNode","webkitIDBCursor","webkitIDBDatabase","webkitIDBDatabaseException","webkitIDBFactory","webkitIDBIndex","webkitIDBKeyRange","webkitIDBObjectStore","webkitIDBRequest","webkitIDBTransaction","webkitIndexedDB","webkitIntent","webkitMediaStream","webkitNotifications","webkitPostMessage","webkitRTCPeerConnection","webkitRequestAnimationFrame","webkitRequestFileSystem","webkitResolveLocalFileSystemURL","webkitStorageInfo","webkitURL","window"]; 

因此，這些不能/不應該」在全球範圍內（至少在Google Chrome中）使用。如果你將它們聲明爲局部範圍內的變量，那就沒問題。
這不會包含所有名稱，但是，因爲arguments僅在函數範圍內可用，例如。

_{注：此功能對您的庫返回所有的全局變量，也}