はじめに
javascriptの一つの問題点として、グローバル変数を自由に作れてしまう事があります。
そこで、グローバル変数の存在を確認するスニペットを作ってみました。
変数に代入してもいいし、コンソールに貼付けて実行結果を吐き出しても良いです。
ただし、ブラウザによって標準のグローバル変数が異なるので以下はchromeのversion35.0の例です。
ただ、他のブラウザでも簡単に作れるので後述する方法で各自試してください。
スニペット
/*chromeの場合*/
(function (self) {
var GLOBALS_ = 'window,Boolean,Number,JSON,DataView,ArrayBuffer,undefined,Proxy,Function,Error,String,Math,WeakSet,eval,Set,document,Intl,Object,Map,URIError,Uint16Array,encodeURI,Array,escape,Int32Array,Int16Array,decodeURI,NaN,Uint8ClampedArray,isNaN,Infinity,external,Promise,parseFloat,Symbol,unescape,WeakMap,RegExp,Uint32Array,ReferenceError,EvalError,Date,RangeError,chrome,top,isFinite,__commandLineAPI,parseInt,SyntaxError,Uint8Array,encodeURIComponent,location,Float64Array,TypeError,decodeURIComponent,Float32Array,Int8Array,speechSynthesis,WebKitSourceBufferList,WebKitSourceBuffer,WebKitMediaSource,XSLTProcessor,VTTCue,TrackEvent,TextTrackList,TextTrackCueList,TextTrackCue,TextTrack,HTMLTrackElement,SpeechSynthesisUtterance,SpeechSynthesisEvent,SharedWorker,MediaKeyEvent,Notification,TimeRanges,MediaError,MediaController,HTMLVideoElement,HTMLSourceElement,HTMLMediaElement,Audio,HTMLAudioElement,MediaSource,FontFace,MediaKeyError,DeviceMotionEvent,webkitSpeechRecognitionEvent,webkitSpeechRecognitionError,webkitSpeechRecognition,webkitSpeechGrammarList,webkitSpeechGrammar,webkitRTCPeerConnection,OfflineAudioContext,AudioContext,webkitOfflineAudioContext,webkitAudioContext,webkitMediaStream,localStorage,sessionStorage,applicationCache,webkitStorageInfo,indexedDB,webkitIndexedDB,crypto,XPathResult,XPathExpression,XPathEvaluator,XMLSerializer,XMLHttpRequestUpload,XMLHttpRequestProgressEvent,XMLHttpRequest,XMLDocument,Worker,Window,WheelEvent,WebSocket,WebKitPoint,WebKitGamepad,WebKitCSSTransformValue,WebKitCSSMatrix,WebKitCSSFilterValue,WebKitCSSFilterRule,WebKitAnimationEvent,WebGLUniformLocation,WebGLTexture,WebGLShaderPrecisionFormat,WebGLShader,WebGLRenderingContext,WebGLRenderbuffer,WebGLProgram,WebGLFramebuffer,WebGLContextEvent,WebGLBuffer,WebGLActiveInfo,ValidityState,URL,UIEvent,TreeWalker,TransitionEvent,TouchList,TouchEvent,Touch,TextMetrics,TextEvent,Text,StyleSheetList,StyleSheet,StorageEvent,Storage,Selection,Screen,SVGZoomEvent,SVGViewSpec,SVGViewElement,SVGUseElement,SVGUnitTypes,SVGTransformList,SVGTransform,SVGTitleElement,SVGTextPositioningElement,SVGTextPathElement,SVGTextElement,SVGTextContentElement,SVGTSpanElement,SVGSymbolElement,SVGSwitchElement,SVGStyleElement,SVGStringList,SVGStopElement,SVGSetElement,SVGScriptElement,SVGSVGElement,SVGRenderingIntent,SVGRectElement,SVGRect,SVGRadialGradientElement,SVGPreserveAspectRatio,SVGPolylineElement,SVGPolygonElement,SVGPointList,SVGPoint,SVGPatternElement,SVGPathSegMovetoRel,SVGPathSegMovetoAbs,SVGPathSegList,SVGPathSegLinetoVerticalRel,SVGPathSegLinetoVerticalAbs,SVGPathSegLinetoRel,SVGPathSegLinetoHorizontalRel,SVGPathSegLinetoHorizontalAbs,SVGPathSegLinetoAbs,SVGPathSegCurvetoQuadraticSmoothRel,SVGPathSegCurvetoQuadraticSmoothAbs,SVGPathSegCurvetoQuadraticRel,SVGPathSegCurvetoQuadraticAbs,SVGPathSegCurvetoCubicSmoothRel,SVGPathSegCurvetoCubicSmoothAbs,SVGPathSegCurvetoCubicRel,SVGPathSegCurvetoCubicAbs,SVGPathSeg,SVGPathSegClosePath,SVGPathSegArcRel,SVGPathSegArcAbs,SVGPathElement,SVGNumberList,SVGNumber,SVGMetadataElement,SVGMatrix,SVGMaskElement,SVGMarkerElement,SVGMPathElement,SVGLinearGradientElement,SVGLineElement,SVGLengthList,SVGLength,SVGImageElement,SVGGraphicsElement,SVGGradientElement,SVGGeometryElement,SVGGElement,SVGForeignObjectElement,SVGFilterElement,SVGFETurbulenceElement,SVGFETileElement,SVGFESpotLightElement,SVGFESpecularLightingElement,SVGFEPointLightElement,SVGFEOffsetElement,SVGFEMorphologyElement,SVGFEMergeNodeElement,SVGFEMergeElement,SVGFEImageElement,SVGFEGaussianBlurElement,SVGFEFuncRElement,SVGFEFuncGElement,SVGFEFuncBElement,SVGFEFuncAElement,SVGFEFloodElement,SVGFEDropShadowElement,SVGFEDistantLightElement,SVGFEDisplacementMapElement,SVGFEDiffuseLightingElement,SVGFEConvolveMatrixElement,SVGFECompositeElement,SVGFEComponentTransferElement,SVGFEColorMatrixElement,SVGFEBlendElement,SVGEllipseElement,SVGElementInstanceList,SVGElementInstance,SVGElement,SVGDiscardElement,SVGDescElement,SVGDefsElement,SVGCursorElement,SVGComponentTransferFunctionElement,SVGClipPathElement,SVGCircleElement,SVGAnimationElement,SVGAnimatedTransformList,SVGAnimatedString,SVGAnimatedRect,SVGAnimatedPreserveAspectRatio,SVGAnimatedNumberList,SVGAnimatedNumber,SVGAnimatedLengthList,SVGAnimatedLength,SVGAnimatedInteger,SVGAnimatedEnumeration,SVGAnimatedBoolean,SVGAnimatedAngle,SVGAnimateTransformElement,SVGAnimateMotionElement,SVGAnimateElement,SVGAngle,SVGAElement,Rect,Range,RTCSessionDescription,RTCIceCandidate,RGBColor,ProgressEvent,ProcessingInstruction,PopStateEvent,Plugin,PluginArray,PerformanceTiming,PerformanceResourceTiming,PerformanceNavigation,PerformanceMeasure,PerformanceMark,PerformanceEntry,Performance,PageTransitionEvent,OverflowEvent,Notation,NodeList,NodeIterator,NodeFilter,Node,Navigator,NamedNodeMap,MutationRecord,MutationObserver,MutationEvent,MouseEvent,MimeType,MimeTypeArray,MessagePort,MessageEvent,MessageChannel,MediaStreamTrack,MediaStreamEvent,MediaList,Location,KeyboardEvent,InputMethodContext,ImageData,ImageBitmap,IDBVersionChangeEvent,IDBTransaction,IDBRequest,IDBOpenDBRequest,IDBObjectStore,IDBKeyRange,IDBIndex,IDBFactory,IDBDatabase,IDBCursorWithValue,IDBCursor,History,HashChangeEvent,HTMLUnknownElement,HTMLUListElement,HTMLTitleElement,HTMLTextAreaElement,HTMLTemplateElement,HTMLTableSectionElement,HTMLTableRowElement,HTMLTableElement,HTMLTableColElement,HTMLTableCellElement,HTMLTableCaptionElement,HTMLStyleElement,HTMLSpanElement,HTMLShadowElement,HTMLSelectElement,HTMLScriptElement,HTMLQuoteElement,HTMLProgressElement,HTMLPreElement,HTMLParamElement,HTMLParagraphElement,HTMLOutputElement,HTMLOptionsCollection,Option,HTMLOptionElement,HTMLOptGroupElement,HTMLObjectElement,HTMLOListElement,HTMLModElement,HTMLMeterElement,HTMLMetaElement,HTMLMenuElement,HTMLMarqueeElement,HTMLMapElement,HTMLLinkElement,HTMLLegendElement,HTMLLabelElement,HTMLLIElement,HTMLKeygenElement,HTMLInputElement,Image,HTMLImageElement,HTMLIFrameElement,HTMLHtmlElement,HTMLHeadingElement,HTMLHeadElement,HTMLHRElement,HTMLFrameSetElement,HTMLFrameElement,HTMLFormElement,HTMLFormControlsCollection,HTMLFontElement,HTMLFieldSetElement,HTMLEmbedElement,HTMLElement,HTMLDocument,HTMLDivElement,HTMLDirectoryElement,HTMLDataListElement,HTMLDListElement,HTMLContentElement,HTMLCollection,HTMLCanvasElement,HTMLButtonElement,HTMLBodyElement,HTMLBaseElement,HTMLBRElement,HTMLAreaElement,HTMLAppletElement,HTMLAnchorElement,HTMLAllCollection,GamepadEvent,Gamepad,FormData,FocusEvent,FileReader,FileList,FileError,File,EventTarget,EventSource,Event,ErrorEvent,Element,DocumentType,DocumentFragment,Document,DeviceOrientationEvent,DataTransferItemList,DataTransfer,DOMTokenList,DOMStringMap,DOMStringList,DOMSettableTokenList,DOMParser,DOMImplementation,DOMException,CustomEvent,Counter,CompositionEvent,Comment,CloseEvent,ClientRectList,ClientRect,CharacterData,CanvasRenderingContext2D,CanvasPattern,CanvasGradient,CSSViewportRule,CSSValueList,CSSValue,CSSUnknownRule,CSSStyleSheet,CSSStyleRule,CSSStyleDeclaration,CSSRuleList,CSSRule,CSSPrimitiveValue,CSSPageRule,CSSMediaRule,CSSKeyframesRule,CSSKeyframeRule,CSSImportRule,CSSFontFaceRule,CSSCharsetRule,CDATASection,Blob,BeforeUnloadEvent,BarProp,AutocompleteErrorEvent,Attr,ApplicationCache,WaveShaperNode,ScriptProcessorNode,PeriodicWave,OscillatorNode,OfflineAudioCompletionEvent,MediaStreamAudioSourceNode,MediaStreamAudioDestinationNode,MediaElementAudioSourceNode,GainNode,DynamicsCompressorNode,DelayNode,ConvolverNode,ChannelSplitterNode,ChannelMergerNode,BiquadFilterNode,AudioProcessingEvent,AudioParam,AudioNode,AudioListener,AudioDestinationNode,AudioBufferSourceNode,AudioBuffer,AnalyserNode,SVGVKernElement,SVGMissingGlyphElement,SVGHKernElement,SVGGlyphRefElement,SVGGlyphElement,SVGFontFaceUriElement,SVGFontFaceSrcElement,SVGFontFaceNameElement,SVGFontFaceFormatElement,SVGFontFaceElement,SVGFontElement,SVGAltGlyphItemElement,SVGAltGlyphElement,SVGAltGlyphDefElement,SpeechInputEvent,WebKitShadowRoot,ShadowRoot,webkitAudioPannerNode,webkitIDBTransaction,webkitIDBRequest,webkitIDBObjectStore,webkitIDBKeyRange,webkitIDBIndex,webkitIDBFactory,webkitIDBDatabase,webkitIDBCursor,WebKitMutationObserver,webkitURL,WebKitTransitionEvent,CSS,performance,console,devicePixelRatio,styleMedia,parent,opener,frames,self,defaultstatus,defaultStatus,status,name,length,closed,pageYOffset,pageXOffset,scrollY,scrollX,screenTop,screenLeft,screenY,screenX,innerWidth,innerHeight,outerWidth,outerHeight,offscreenBuffering,frameElement,event,clientInformation,navigator,toolbar,statusbar,scrollbars,personalbar,menubar,locationbar,history,screen'.split(',');
var g_ = Object.getOwnPropertyNames(self);
return g_.filter(function(x) {return !~GLOBALS_.indexOf(x);});
})(this);
他のブラウザやバージョン違いでの作り方
まずは、そのブラウザをブランクページで開きます。
chromeであれば、urlにabout:blankと打ち込みます
その後、コンソールを開いてください。そこに次のように打ち込んで結果を上記のGLOBALS_に代入するとそのブラウザ用のものが出来ます。
Object.getOwnPropertyNames(this);
(上記では、一度カンマでjoinしたものを代入し、splitしていますが、そのままでもかまいません)
他のウェブサービスを参考する
例えばQiitaの記事ページで実行すると次のように出力されます
["_", "___jsl", "optimizely", "mixpanel", "loadrunner", "Qiita", "_gaq", "gaGlobal", "__twitterIntentHandler", "store", "_gat", "jQuery1110007918387488462031", "bundle", "optly", "google_tag_manager", "$", "osapi", "provide", "Backbone", "gadgets", "define", "Iframe", "GoogleAnalyticsObject", "__twttrlr", "iframes", "I18n", "IframeProxy", "__gapi_jstiming__", "twttr", "IframeBase", "FB", "jQuery", "shindig", "Hatena", "optimizelyCode", "ga", "key", "ToolbarApi", "dataLayer", "iframer", "using", "IframeWindow", "gapi", "gaplugins", "JST"]
随分といろいろなライブラリを利用している見たいですね。
参考にしたいウェブサービスがどのようなライブラリが読み込まれているのかを、参考程度ですがさくっと見る事が出来るかもしれません（保証無し）