[SOLVED] Js help

Question

I had this challange and cant figure out how it work

var x = 1e-1;
var y = -String(-x*10);
alert(y);

// output 1

What is e, what is -String and how this work?

Answer 1

e means the scientific notation:
1e-1 = 1 * 10^-1 = 0.1
-x * 10 = -0.1 * 10 = -1
Then, it's turned into a string ("-1"), then made negative; which makes it a number again. -(-1) equals 1.

Answer 2

Thank you Airree