Proposal status

Simple examples

Example of ad-hoc extension methods and accessors

// define two extension methodsconst ::toArray=function(){return[...this]}const ::toSet=function(){returnnewSet(this)}// define a extension accessorconst ::allDivs={get(){returnthis.querySelectorAll('div')}}// reuse built-in prototype methods and accessorsconst ::flatMap=Array.prototype.flatMapconst ::size=Object.getOwnPropertyDescriptor(Set.prototype,'size')// Use extension methods and accesors to calculate// the count of all classes of div element.letclassCount=document::allDivs::flatMap(e=>e.classList::toArray())::toSet()::size

// define two extension methodsconst$toArray=function(){return[...this]}const$toSet=function(){returnnewSet(this)}// define a extension accessorconst$allDivs={get(){returnthis.querySelectorAll('div')}}// reuse built-in prototype method and accessorconst$flatMap=Array.prototype.flatMapconst$size=Object.getOwnPropertyDescriptor(Set.prototype,'size')// Use extension methods and accesors to calculate// the count of all classes of div element.let$$=$allDivs.get.call(document)$=$flatMap.call($,e=>$toArray.call(e.classList))$=$toSet.call($)$=$size.get.call($)letclassCount=$

Example of using constructors or namespace object as extensions

// util.jsexportconsttoArray=iterable=>[...iterable]exportconsttoSet=iterable=>newSet(iterable)

import*asutilfrom'./util.js'const ::allDivs={get(){returnthis.querySelectorAll('div')}}letclassCount=document::allDivs::Array:flatMap(e=>e.classList::util:toArray())::util:toSet()::Set:size

import*asutilfrom'./util.js'const$allDivs={get(){returnthis.querySelectorAll('div')}}let$$=$allDivs.get.call(document)$=Array.prototype.flatMap.call($,e=>util.toArray(e.classList))$=util.toSet($)$=Object.getOwnPropertyDescriptor(Set.prototype,'size').get.call($)letclassCount=$

Changes of the old bind operator proposal

Other matrials