$ mol_strict: How about me [object Object] this undefined NaN of yours‼

Hello, my name is Dmitry Karlovsky and I ... do not forgive mistakes. As soon as I see it, I immediately throw something extremely heavy. And how hard the work of a JS programmer is ...

class Foo extends Object {}
const foo = new Foo

`, ${ foo }!`
// " [object Object]!"

`     ${ foo / 1000 }  .`
// "     NaN  ."

`  "${ 'foo'[4] }" - .`
// "  "undefined" - ."

`  ${ foo.length - 1 }     .`
// "  NaN     ."
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

There are several ways to ease his suffering.

1. Cover yourself with a typescript. But in runtime, the feet still remain bare, and someone always steps on them.
2. To impose checks. But you hesitate a little and the runtime rake immediately hits the head.
3. Fix JS. Don't even hope.
4. Fix JS runtime. Well, let's think ..

JS dynamic typing problems arise for 2 main reasons:

• Automatic (and sometimes inappropriate) typecasting when a value of one type is used in a context intended for another.
• Return undefined as the value of un-declared fields.

. JS , . . , :

Object.prototype[ Symbol.toPrimitive ] = function() {
    throw new TypeError( `Field Symbol(Symbol.toPrimitive) is not defined` )
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, , Symbol.toPrimitive



.

, . - … - ! … , .

- , . JS — . , :

export let $mol_strict_object = new Proxy( {}, {

    get( obj: object, field: PropertyKey, proxy: object ) {
        const name = JSON.stringify( String( field ) )
        throw new TypeError( `Field ${ name } is not defined` )
    },

})
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, prototype



Object



, , . Object.prototype



— null



. Object



:

:

for( const name of Reflect.ownKeys( $ ) ) {
    // ...
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, :

const func = Reflect.getOwnPropertyDescriptor( globalThis, name )!.value
if( typeof func !== 'function' ) continue
if(!( 'prototype' in func )) continue
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, globalThis[name]



, .

, Object



:

const proto = func.prototype
if( Reflect.getPrototypeOf( proto ) !== Object.prototype ) continue
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, , Object.prototype



:

Reflect.setPrototypeOf( proto, $mol_strict_object )
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, , . , .

, , Object, , EventTarget, .

CSSStyleDeclaration



: ( , ), , , 89 style



dom-:

( <div style={{ color: 'red' }} /> ).outerHTML // <div></div>
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

.

… :

class Foo {}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

. :

class Foo extends Object {}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

… . Object



:

globalThis.Object = function $mol_strict_object( this: object, arg: any ) {
    let res = Object_orig.call( this, arg )
    return this instanceof $mol_strict_object ? this : res
}

Reflect.setPrototypeOf( Object, Reflect.getPrototypeOf({}) )
Reflect.setPrototypeOf( Object.prototype, $mol_strict_object )
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, Object



, .

, ...

class Foo extends Object {}
const foo = new Foo

`, ${ foo }!`
// TypeError: Field "Symbol(Symbol.toPrimitive)" is not defined

`     ${ foo / 1000 }  .`
// TypeError: Field "Symbol(Symbol.toPrimitive)" is not defined

`  "${ 'foo'[4] }" - .`
// TypeError: Field "4" is not defined

`  ${ foo.length - 1 }     .`
// TypeError: Field "length" is not defined
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, , :

, - . — .

, : JavaScript ?.

: $mol_strict.

NPM - :

import "mol_strict"
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

:

require("mol_strict")
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

$mol : $mol: Usage from NPM ecosystem.

JS , :

• ( . , , , .)
• UfoStation Chat ( — .)

, _jinnin , JS, UX .