BrowserVersionOwn?TypeAs String
ALAFISH89.0.4389???
Chrome38.0.2125???
Edge17.17134.0???
Firefox51.0.0???
FxiOS33.0.0???
IE10.0.0???
Safari4.0.0???
Safari10.1.2ownobject[object WebKitNamespacePrototype]
Safari14.0.0ownobject[object WebKitNamespace]
Safari537.36.0???

PropertiesALAFISHChromeEdgeFirefoxFxiOSIESafari
constructor?????? 10.0.0
messageHandlers?????? 10.0.0