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6.2: Scope and Closure - Coggle Diagram

- - - - variables, functions, etc
      - are accessible within your code
  - - - is the function in which they are defined
    - - is defined outside of a function
      - it's part of the global scope
      - accessible to all code
    - - is variables declared with let
      - let creates block scope
        
        defined by curly braces
      - function test() { let num1 = 1; if (num1 === 1) { let num2 = 10; console.log(num1, num2); } console.log(num1, num2); } test();
      - outputs
        
        > Uncaught ReferenceError: num2 is not defined
      - the scope for num2
        
        is the block created by the if statement
      - the scope for num1
        
        is the block created by the function test
- - - - outputs
        
        > 5 > undefined
        
        immediately
      - prints 5 to the console
        
        then function ends
  - - - outputs
        
        > undefined > 5
        
        undefined
        
        immediately
        
        when fn1 finishes
        
        5
        
        3 seconds later
        
        when fn2 is called
        
        :explode: fn2 can still access a and b #
        
        still retains the scope of fn1 #
        
        :tada: this is closure
  - - - bundled together with
        
        references to its surrounding state
      - a function
    - - access to an outer function's scope
      - from an inner function
    - - every time a function is created
      - at function creation time