Optimizing code to map numbers 1 - 25 uniformly to 5 colors

Question

I am currently learning JavaScript, and I made this code (and it works fine) but I know that there must be a way to automate this better. I'm little bit fuzzy on loops, but from what I know of them, I don't know that one could be used in this situation:

function calculation() {

var num = document.getElementById("input").value;
var trCalc = num % 25;

var tipColorName = document.getElementById("tipColorName");
var ringColorName = document.getElementById("ringColorName");

var tipBlock = document.getElementById("tipBlock");
var ringBlock = document.getElementById("ringBlock");

// Pair Calculations

if (trCalc > 0 && trCalc <= 5) {
    tipColorName.innerHTML = "White";
    tipBlock.setAttribute("style", "background-color: #f2f2f2; color: #2f2f2f;");
}
if (trCalc > 5 && trCalc <= 10) {
    tipColorName.innerHTML = "Red";
    tipBlock.setAttribute("style", "background-color: #e24341; color: white;");
}
if (trCalc > 10 && trCalc <= 15) {
    tipColorName.innerHTML = "Black";
    tipBlock.setAttribute("style", "background-color: #2f2f2f; color: white;");
}
if (trCalc > 15 && trCalc <= 20) {
    tipColorName.innerHTML = "Yellow";
    tipBlock.setAttribute("style", "background-color: #f4ca37; color: #2f2f2f;");
}
if (trCalc > 20 && trCalc <= 24 || num % 25 == 0 && num > 0 ) {
    tipColorName.innerHTML = "Violet";
    tipBlock.setAttribute("style", "background-color: #844ae0; color: white;");
}
if ([1, 6, 11, 16, 21].includes(trCalc)) {
    ringColorName.innerHTML = "Blue";
    ringBlock.setAttribute("style", "background-color: #426ffe; color: white;");
}
if ([2, 7, 12, 17, 22].includes(trCalc)) {
    ringColorName.innerHTML = "Orange";
    ringBlock.setAttribute("style", "background-color: #f27f42; color: #2f2f2f;");
}
if ([3, 8, 13, 18, 23].includes(trCalc)) {
    ringColorName.innerHTML = "Green";
    ringBlock.setAttribute("style", "background-color: #25d366; color: white;");
}
if ([4, 9, 14, 19, 24].includes(trCalc)) {
    ringColorName.innerHTML = "Brown";
    ringBlock.setAttribute("style", "background-color: #917260; color: #2f2f2f;");
}
if ([5, 10, 15, 20 ].includes(trCalc) || num % 25 == 0 && num > 0 ) {
    ringColorName.innerHTML = "Slate";
    ringBlock.setAttribute("style", "background-color: grey; color: #2f2f2f;");
}

Any help is appreciated!

Answer 1

Here is how I would optimize it:

const tipColorNames = ['White', 'Red', 'Black', 'Yellow', 'Violet'];
const tipStyles = [
  "background-color: #f2f2f2; color: #2f2f2f;",
  "background-color: #e24341; color: white;",
  "background-color: #2f2f2f; color: white;",
  "background-color: #f4ca37; color: #2f2f2f;",
  "background-color: #844ae0; color: white;",
];
const ringColorNames = ['Blue', 'Orange', 'Green', 'Brown', 'Slate'];
const ringStyles = [
  "background-color: #426ffe; color: white;",
  "background-color: #f27f42; color: #2f2f2f;",
  "background-color: #25d366; color: white;",
  "background-color: #917260; color: #2f2f2f;",
  "background-color: grey; color: #2f2f2f;",
];

const divisor = 5;
const numColors = tipColorNames.length;

function calculation() {
  var num = document.getElementById("input").value;
  var trCalc = num % (divisor * numColors);

  var tipColorName = document.getElementById("tipColorName");
  var ringColorName = document.getElementById("ringColorName");

  var tipBlock = document.getElementById("tipBlock");
  var ringBlock = document.getElementById("ringBlock");

  const tipColorIndex = trCalc === 0 && num > 0
    ? numColors - 1
    : (trCalc - 1) / divisor;

  tipColorName.innerHTML = tipColorNames[tipColorIndex];
  tipBlock.setAttribute('style', tipStyles[tipColorIndex]);

  const ringColorIndex = (num - 1) % numColors;
  ringColorName.innerHTML = ringColorNames[ringColorIndex];
  ringBlock.setAttribute('style', ringStyles[ringColorIndex]);
}

Answer 2

Optimization and minification are really two different things. look at this site for minification http://closure-compiler.appspot.com/home.

As far as optimization there are a couple of things you could do.

You could look at using one function to change your styling. which would clean up your code and make it more readable. Something like:

changeStyles(innerColor,bgColor,color){
  ringColorName.innerHTML = innerColor;
  ringBlock.setAttribute("style", "background-color: "+bgColor+"; color: "+color+";") 
}

Then your if statements would look something like this:

if ([1, 6, 11, 16, 21].includes(trCalc)) {
   changeStyles("White","#f2f2f2","#2f2f2f");
}

You could look at the modulo operator. For the last five if statements it looks like you could do foo = trCalc % 5 followed by a switch(foo). Might look something like this.

foo = trCalc % 5
switch(foo) {
    case 0:
        changeStyles("White","#f2f2f2","#2f2f2f");
        break;
    case 1:
        changeStyles("White","#f2f2f2","#2f2f2f");
        break;
    case 2:
        changeStyles("White","#f2f2f2","#2f2f2f");
        break;
    case 3:
        changeStyles("White","#f2f2f2","#2f2f2f");
        break;
    case 4:
        changeStyles("White","#f2f2f2","#2f2f2f");
        break;
}

Of course, you would have plug the appropriate colors into the function changeColors. Hopefully that gives you some ideas.