what does modulou do in javascript code example

Example 1: js modulo

// The JS % operater is REMAINDER not MODULO
// For modulo behaviour use
function mod(n, m) {
  return ((n % m) + m) % m;
}

Example 2: modulo operator in javascript

// % in JS is the remainder, not modulo
//here is Shanimal's function for modulo operation
// n = your number, m = number to mod by
var mod = function (n, m) {
    var remain = n % m;
    return Math.floor(remain >= 0 ? remain : remain + m);
};
mod(5,22)   // 5
mod(25,22)  // 3
mod(-1,22)  // 21
mod(-2,22)  // 20
mod(0,22)   // 0
mod(-1,22)  // 21
mod(-21,22) // 1