如何化简分数？

Question

I've been working for awhile on a huge mathematical multitool and I'm making a fraction simplifier in it (all with alerts). I tried the following, what did I do wrong?

 if (confirm("Confirm to select a program\nCurrent program: Fraction Simplifier") == true) { var numerator = prompt("Enter the numerator"); var denominator = prompt("Enter the denominator"); var nFrac = numerator; var dFrac = denominator; simpFrac(); alert(numerator + "/" + denominator + " simplified is " + nFrac + "/" + dFrac); }; function simpFrac() { for (var i = 1; i < dFrac; i++) { fracV = fracV + 1; if (Number.isInteger(nFrac / fracV) && Number.isInteger(dFrac / fracV)) { nFrac = nFrac / fracV; dFrac = dFrac / fracV; }; }; };

Answer 1

Divide the numerator and the denominator by the GCD.

 const GCD = (a, b) => b? GCD(b, a % b): a; let numerator = 15, denominator = 18; let div = GCD(numerator, denominator); console.log(`${numerator}/${denominator} simplifies to ${numerator/div}/${denominator/div}`);

Answer 2

someone answered and deleted their answer, I implemented their method. It worked. Changed to

if (confirm("Confirm to select a program\nCurrent program: Fraction Simplifier") == true) {
    if (confirm("Confirm to select a program\nCurrent program: Fraction Simplifier") == true) {
    var numerator = prompt("Enter the numerator");
    var denominator = prompt("Enter the denominator");
    var GCD = (a, b) => b ? GCD(b, a % b) : a;
    let div = GCD(numerator, denominator);
    alert(numerator + "/" + denominator + " simplifies to " + numerator / div + "/" + denominator / div + ".");