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JS: this & object prototypes (Objects (Immutability (Freeze Object…

- - - - it calls Object.seal(..) on the object and mark all properties as writable: false
    - - it calls Object.preventExtensions(..) on the object and set configurable: false to all properties. But you can still modify properties values
    - - If you want to prevent an object from having new properties added to it, but otherwise leave the rest of the object's properties alone, call Object.preventExtensions(..)
        
        In non-strict mode, the creation of b property fails silently. In strict mode, it throws a TypeError
    - - By combining writable:false and configurable:false, you can essentially create a constant
  - - - If it can't find the value it returns undefinded
        
        can be overwritten with get() and set() functions within the object
    - - Before assigning new value [[Put]] checks, among them checking for writable
  - - - assigning new value is silently failing in non-strict mode
      - assigning new value results in TypeError in strict mode
    - - setting configurable to false is one way action and cannot be undone. If we try to change property which is configurable = false we get TypeError regardless of strict mode
      - if configurable = false the only descriptor which can be changed is writable to the false value. It will be an error if we try to change writable to true
      - if configurable = false than you can not delete property from the object by delete operator. It will fail silently
- - - - Is the function called with new?
        
        yes
        
        this is the newly constracted object
        
        no
        
        is the function callled with call or apply
        
        yes
        
        this is specified object
        
        no
        
        is the function called with a context (owning or containing object?
        
        yes
        
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        no
        
        1 more item...
    - - When call() or apply() called with parameter null or undefined. this is resolved with default rule e.g. global object