What's the difference between variable definition and declaration in JavaScript?

Question

Is this a variable definition or declaration? And why?

var x;

..and is the memory reserved for x after this st

Answer 1

In simple terms,

undefined means value to the variable is not defined.

not defined means the variable itself is not defined.

var x; //value is not defined. So, x //undefined

//y variable is not declared or defined. So, y // y is not defined