Is this right to write document.write(x=4 + ++x);

Question

it shows error when i run it like this. but if i first use document.write(x=4,++x); //45 and then write again document.write(x=4 + ++x ) it surprisingly runs and shows me output //4510

can anyone tell me why

Answer 1

After the first write, x is 5 and 45 is written, then you do x=4 + ++x which evaluates to x=4 + 6 which is 10, so it writes 10, leaving you with 4510.