Why we use var, var is harder than document.write anyone can tell me?

Question

Var harder than document.write

Answer 1

hmm lets see..okay got one.

when we should use var:
var txt = prompt();
document.write(txt.eval());

what happens if we dont:

i cant even right this line of code cuz no matter what it wont work so thats why var is important

Answer 2

Var is short for variable. You store values in it.
The document. write() method writes a string of text to a document.

Your question does not make much sense.

Answer 3

Wrong?