I came across a statement that has left my head confused.
Assume x >= 0
(x - 1 ? 16:11)
Apparently this code has the same response as
(x > 1 ? 16:11)
Can someone explain how the minus one works? I thought that conditional operators had to provide a true or false result. I don't understand how an integer can fit into a conditional operator.
In the code:
(x - 1 ? 16 : 11)
if x is equal to 1, x - 1 is 0 and 0 is falsy so the expression evaluates to 11. Otherwise, x - 1 is truthy and the expression evaluates to 16.
You could use some values to get an idea what is going on.
x - 1 ? 16 : 11
-1 - 1 -2 truthy -> 16
0 - 1 -1 truthy -> 16
1 - 1 0 falsy -> 11
2 - 1 1 truthy -> 16
3 - 1 2 truthy -> 16
Based on this, the condition could be rewritten to
x !== 1 ? 16 : 11
The conditional operator is evaluating the result of your expression.
Assuming x = 2 the results would be:
2 - 1 = 1
2 > 1 = true
Assuming x = 1 the results would be:
1 - 1 = 0
1 > 1 = false
0 will be treated as false. 1 as true.
So both expressions will have the same result.
But be aware:
If you do use negative numbers the expressions will have different results, since negative numbers will be treated as true by the conditional operator.
-3 - 1 = -4 => true
-3 > 1 = false
values greater than 0 or less than 0 are taken as true in conditional statements, and zero is taken as false
(1)?"true": "false";
(0)?"true": "false";
console.log((-1)? "true": "false");
console.log((1)? "true": "false");
console.log((0)? "true": "false");