mindboggling JS code - if(x)...

Question

It's simple, but I don't quite get it:

var x = 1;
if(x){
x=0;
}
if(x){
x=1;
}
alert(x);

If I understand it right, the first "if" changes the x value to 0, and the second "if" thinks x is no longer x. but why? X is changed, but it is still x......

Answer 1

x = 1

if (1) { x = 0 }
1 means true -> x = 0

if (0) { x = 1 }
0 means false -> Nothing happens.

alert(x)
x = 0 is alerted.

Answer 2

JS evaluates 1 to true and 0 to false. Therefore only the instruction of the first if block will execute, changing the value of x from 1 to 0.

if 1==true
x becomes 0

if (0==true)
//doesn't execute, therefore x remains 0