var a,b,c,d; b=a; c=a+b; d=c-a; alert(d==b);

Question

//output= false //do u have any explanation?

Answer 1

you didn't assign any value. so NaN != undefined

Answer 2

Elie! why have assigned d to 2??

Answer 3

the coding missing numbers, it give undefined if there's no numbers...i gived you example with numbers

Answer 4

ok, I mean the example is wrong

Answer 5

yep to get false you need to assign a number to var a b c d

Answer 6

best practice is to declare each variable separate, not all ina single line.
then assign each variable immediately a value, request memory resources and initialization go should go in one step if possible.

Answer 7

par example
a=4
b=5
c=6
d=1

b=a ----> b=4
c=a+b -----> c=4+5 ---->c=9
d=c-a ----> d=6-4 ---->d=2

d==b ---> 2==4

Not Equal --> false