is switch(true) {… valid javascript?

Question

I recently came across code where a switch statement seemed reversed with the answer (boolean) in the switch and the expressions in the case. The code ran fine as intended b

Answer 1

The cases will get executed based on value of y.

Because the conditions depend on the value of y. As said by aefxx, it is an other form of:

if (y < 20) {
    // ...
} elseif (y < 60) {
    // ...
} elseif ( y < 130) {
    // ...
}