Execution Stack

How JS works behind the scene.

A. Hoisting

• JS loades Exection stack for execution thread.
• then declares the property and method
• then executes the code flow.
• note: if var is used in code without declation then JS declares thar property in global execution stack.

B. Execution Stack

1. Understand it with for below prg:

   global stack --> 
   - method declaration: first(), third()
   - property declation : a
   
   
   first() method stack --> 
   - method declaration: second()
   - property declation : b
   

2. first() is called at line 59

3. New Execution stack will be formed for first(), for its execution, on top of global stack.
4. Again declaration will happen, followed by execution then.

note 1 : property/method declared in parent stack will be avialble to child (and nested child). See nested flow eg:

note 2 : method-expression wont be declared inside stack. eg: line 13 below.

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1. Theory to understand it:
2. default stack is global stack to execute the current JS code. it act as starting execution point.

2.1 VO

• creation Phase: VO object holds 3 things --> argument, funtion and property
• Another simple eg:

2.2 Scope chain

• in JS, there are only 2 scope - global and local(each function)
• lexical scoping chain --> if function defined inside anothor function, then it will be scope inside scope.
• execution stack defines scope chaining.

• It will to understand where to access particular method.proprty. simple rule --> child scope will have access to parent scope, thats all.

• note: difference between scope chain and execution stack:

2.3 this

• this will be window object for prg mentioned at point 2.
• this will be john object in below prg:

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