if between two numbers javascript

// Between any two numbers
Math.floor(Math.random() * (max - min + 1)) + min;

// Between 0 and max
Math.floor(Math.random() * (max + 1));

// Between 1 and max
Math.floor(Math.random() * max) + 1;

let a = 4;
let b = 5;
document.write(a + b);

var difference = function (a, b) { return Math.abs(a - b); }

var x = 2 + 3;
//x = 5

if (500 < thenumber && thenumber < 600) {
  // ...
}