square and multiply algorithm

squareandmultiply.js

function sqm(base, exponent, mod) {
    let ze = 1; let a = base;
    while (exponent) {
        if (exponent & 1) ze = (ze * a) % mod;
        a = (a * a) % mod;
        exponent = exponent >> 1;
        // console.log("Ze: " + ze + " A: " + a);
    }
    return ze;
}