Closure behavior experimented

scope closure

function foo(){
  var a = 2;
  
  function bar(){
    console.log( a ); 
  }
  
  bar(); // 2 not-closure, regular lexical scope actually
}

foo();

/*======= closure ==============*/
function foo(){
  var a = 2;
  
  function bar(){
    console.log(a);
  }
  
  return bar;
}

var baz = foo();

baz(); // 2 -- closure observed here

/*============== weird piece of code ====================*/
for (var i=1; i<=5; i++){
  (function(){
    setTimeout(function time(){
      console.log(i);
    }, i*1000);
  })();
}

// result is 6 - for 5 times but we expected 1,2,3,4,5
for (var i=1; i<=5; i++){
  (function(i){
    setTimeout(function time(){
      console.log(i);
    }, i*1000);
  })(i);
}

// result is 1,2,3,4,5 because we created scope variable j to remember value of i in the scope of closure

for (var i=1; i<=5; i++){
  let j = i;
  setTimeout(function time(){
    console.log(j);
  }, j*1000);
}

// works as above because let defines for each loop scope.

for (let i=1; i<=5; i++){
  setTimeout(function time(){
    console.log(i);
  }, i*1000);
}

// works as above because let defines for each loop scope.