Question

x = 1;    
if(x = 10) {x = 1;} 
else {x = x + 1;}
alert (x);

The result is always 1, instead of 1,2,3...

Answer 1

Replace

if(x = 10) {x = 1;} 

with

if(x == 10) {x = 1;} 

Because x=10 returns 10, which in a test evaluates as true, and thus the code {x = 1;} is executed.

From the MDN about if…else :

Any value that is not undefined, null, 0, NaN, or the empty string
(“”), and any object, including a Boolean object whose value is false,
evaluates to true when passed to a conditional statement