Negative numbers in JavaScript

Numbers can be negative. To do this, put a minus sign before the number:

let a = -1;
alert(a); // shows -1

A minus sign can be written to both numbers and variables:

let a = 1;
let b = -a; // the contents of a with the opposite sign is written to b
alert(b);   // shows -1

Or like this:

let a = 1;
alert(-a); // shows -1

Create the variable a with the value -100. Display this value on the screen.

Create the variable a, write some positive or negative number to it. Display this value with the opposite sign on the screen.