What are the difference between undefined and not defined in JavaScrip

What are the difference between undefined and not defined in JavaScript?

Answer»

	undefined	Not DEFINED
1.	A variable was DECLARED with a KEYWORD "var" but not assigned with a value.	A variable have not been declared without assignment:
2.	Example : var a = 1, b; console.log(a) //1 console.log(b) //undefined	Example : var a = 1, b; console.log(F) // not defined