Scopes by example

Creating global variable

  a = 1;

Creating global variable in local scope

        //Global scope
          { //Local scope 1
            {//Local scope 2
              //Create global variable from local scope
              a = 4;
            }
          }
          // In this scope a = 4
          return a;

Temporary local variables

        //Global scope
          { //Local scope 1
            var a; //Create empty variable in local scope 1
            {//Local scope 2
              //This will set variable to top-most scope which contains
              //definition for variable, which is Local scope 1
              a = 4;
            }
          }
          //Global scope still empty

Variable resolving rules

        //Global scope
          { //Local scope 1
            var a; //Create empty variable in local scope 1
            {//Local scope 2
              //This will set variable to top-most scope which contains
              //definition for variable, which is Local scope 1
              a = 5;
              { //Local scope 3
                var a; //Create empty variable in local scope 3
                //This will set variable to top-most scope which contains
                //definition for variable, which is Local scope 1
                global:a = 4;
                a = 3; // Set local variable
              }
            }
            //Create variable in global scope equal to current value of a in this scope
            b = a;
          }
          //b = 4;
          return b;

Temporary variables in for loop

          var sum = 0;
          for (var x=0; x<10; x++){
            var temp = x;
            sum += x;
          }
          //Here temp and x variables are absent
          return sum;