Hoisting

Hoisting is JavaScript's default behavior of moving all declarations to the top of the current scope (script or function). Be carefull that only declaration gets hoisted NOT the initialitations

var x = 5;alert("x is  = " + x + ". y is = " + y); //result => x is = 5. y is = undefined.var y = 7;

note that the code doesn't produce the error "y is not defined" like it would if we would omit y. It executes but not in the way you would want.