jsオブジェクト(3)

JavaScriptにおけるオブジェクトの分類

A. ホストオブジェクト JavaScript のホスト環境によって提供されるオブジェクトで、その動作はホスト環境によって完全に決定されます。
ブラウザオブジェクト

B. 組み込みオブジェクト JavaScript 言語が提供するオブジェクト

 a. Intrinsic objects Instances of objects that are automatically created with JavaScript runtime creation, as specified by the standard
     Three values:
         Infinity, NaN, undefined
     Nine functions:
         eval
         isFinite
         isNaN
         parseFloat
         parseInt
         decodeURI
         decodeURIComponent
         encodeURI
         encodeURIComponent
     Some constructors:
         Array, Date, RegExp, Promise, Proxy, Map, WeakMap, Set, WeakSet, Function, Boolean, String, Number, Symbol, Object, Error, EvalError, RangeError. ReferenceError, SyntaxError, TypeError, URIError, ArrayBuffer, SharedArrayBuffer, DataView, Typed Array, Float32Array, Float64Array Int8Array, Int16Array, Int32Array, UInt8Array, UInt16Array, UInt32Array, UInt8ClampedArray.
     Four objects used as namespaces.
         Atomics
         JSON
         Math
         Reflect
     Find all intrinsic objects : Use breadth-first search to find all properties and Getters/Setters of these objects to get all intrinsic objects of JS

         var set = new Set();
         var objects = [eval,isFinite,isNaN,parseFloat,parseInt,decodeURI,decodeURIComponent,encodeURI,encodeURIComponent,Array,Date,RegExp, Promise,Proxy,Map,WeakMap,Set,WeakSet,Function,Boolean,String,Number,Symbol,Object,Error,EvalError,RangeError,ReferenceError, SyntaxError,TypeError,URIError,ArrayBuffer,SharedArrayBuffer,DataView,Float32Array,Float64Array,Int8Array,Int16Array,Int32Array, Uint8Array,Uint16Array,Uint32Array,Uint8ClampedArray,Atomics,JSON,Math,Reflect];
         objects.forEach(o => set.add(o));

         for(var i = 0; i < objects.length; i++) {
             var o = objects[i]
             for(var p of Object.getOwnPropertyNames(o)) {
                 var d = Object.getOwnPropertyDescriptor(o, p)
                 if( (d.value ! == null && typeof d.value === "object") || (typeof d.value === "function"))
                     if(!set.has(d.value))
                         set.add(d.value), objects.push(d.value);
                 if( d.get )
                     if(!set.has(d.get))
                         set.add(d.get), objects.push(d.get);
                 if( d.set )
                     if(!set.has(d.set))
                         set.add(d.set), objects.push(d.set);
             }
         }

 b. Native objects Objects that can be created by the user through built-in constructors such as Array, RegExp, or special syntax
    New objects can be created by the new operation, called native objects

         typeof new Date // object
         typeof Date() // string
         Their implementations of [[call]] [[construct]] do not always have the same result

         The execution process of new:
             A. create a new object using the prototype property of the constructor as the prototype
             B. Pass this and the call argument to the constructor for execution
             C. If the constructor returns an object, return it, otherwise return to the first step of creation

         [[construct]] execution procedure:
             Create a new object with Object.prototype as the prototype.
             Execute the [[call]] of the function with the new object as this.
             If the return value of [[call]] is an object, then this object is returned, otherwise the new object created in the first step is returned.

                 function cls(){
                     this.a = 100;
                     return {
                         getValue:() => this.a
                     }
                 }
                 var o = new cls;
                 o.getValue(); //100
                 //a is never accessible outside

         Special Behavior Objects
             Array: The length property of Array changes automatically based on the largest subscript.
             Object.prototype: as the default prototype of all normal objects, you can't set a prototype for it anymore.
             String: To support subscript operations, access to the positive integer property of String goes to the string.
             Arguments: the non-negative integer subscript property of arguments is linked to the corresponding variable.
             The namespace object of the module: it has many special features and is completely different from the normal object, so try to use it only for import.
             Arrays of types and array buffers: associated with memory blocks, with special subscripting operations.
             function after bind: associated with the original function.

    * Constructors in JS:

          Basic types
              Boolean
              String
              Number
              Symbol
              Object

          Basic Functions and Data Structures
              Array
              Date
              RegExp
              Promise
              Proxy
              Map
              WeakMap
              Set
              WeakSet
              Function

          Error Type
              Error
              EvalError
              RangeError
              ReferenceRrror
              SyntaxError
              TypeError
              URIError

          Binary Operations
              ArrayBuffer
              SharedArrayBuffer
              DataView

          Arrays with types
              Float32Array
              Float64Array
              int8Array
              int16Array
              int32Array
              UInt8Array
              UInt16Array
              UInt32Array
              UInt8ClampedArray

    Most of the objects created by these constructors use private fields:
         Error: [[ErrorData]]
         Boolean: [[BooleanData]]
         Number: [[NumberData]]
         Date: [[DateValue]]
         RegExp: [[RegExpMatcher]]
         Symbol: [[SymbolData]]
         Map: [[MapData]]


 c. Common object An object created by the {} syntax, the Object constructor, or the class keyword defining the class, which can be inherited by the prototype

     Function objects
         has a [[call]] private field
         The [[call]] private field must be a function defined in an engine that accepts this value and call parameters and generates a domain switch
     Constructor objects
         has [[construct]] private fields