在正确的输出上更改颜色

如何解决在正确的输出上更改颜色

我希望在收到正确的加密或解密信息后（用户在密钥字段中输入1到26之间的数字并按加密/解密时，或者当他得到的输出不同于“未定义”序列）。这可能吗？如果是这样，我该怎么办？ 谢谢

let inps = [];
let buttons = [];
let alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
let backImage;

function preload (){
  backImage = loadImage('images/back.jpg')
}

function setup() {
  
  createCanvas(600,600);
  
//  Type here your plain or encryted message
  inps.push(createElement('textarea'));
  inps[0].position(20,70);
  inps[0].size(550,150);
  inps[0].style('background','#3C3C3B');
  inps[0].style('color','#ffffff');
  
  
//   Key
  inps.push(createInput(' Insert number from 1 to 26'));
  inps[1].position(20,290);
  inps[1].size(200,20);
  inps[1].style('background','#3C3C3B');
  inps[1].style('color','#ffffff');
  
//  Encrypted / Decrypted message
  inps.push(createElement('textarea'));
  inps[2].position(20,370);
  inps[2].size(550,150);
  inps[2].style('background','#3C3C3B');
  inps[2].style('color','#ffffff');

  
  buttons.push(createButton('Encrypt'));
  buttons[0].position(370,275);
  buttons[0].size(100,50);
  buttons[0].mousePressed(encrypt);
  
  buttons.push(createButton('Decrypt'));
  buttons[1].position(475,275);
  buttons[1].size(100,50);
  buttons[1].mousePressed(decrypt);
  
  noStroke();

}

function draw() {
  background(backImage);
  fill(255)
  text('Type here your plain or encryted message',20,60);
  text('Encrypted / Decrypted message',360);
  text('Key',280);
  light()
  blinkRed()
  // blinkGreen()
}

function light(){
  for (let x = 0; x < 3; x++){
     noStroke();
     fill(255)
     ellipse(25*x+510,30,20);
}
}
function blinkRed(){
  for (let i = 0; i < 3; i++){
    noStroke();
     if(frameCount % 60 < 30) {
    fill(50);
    } else {
    fill(255,0)
  } 
    ellipse(25*i+510,15);
  }
}
// function blinkGreen(){
//   for (let i = 0; i < 3; i++){
//     noStroke();
//      if(frameCount % 60 < 30 && buttons[0].mousePressed) {
//     fill(50);
//     } else {
//     fill(0,255,0)
//   ellipse(25*i+510,15);
//   }
//   }
// }


function encrypt() {
  const initial = inps[0].value().toUpperCase();
  const shift = int(inps[1].value()) % 26;
  let output = '';
  for (let i = 0; i < initial.length; i++) {
    if (alphabet.includes(initial[i])) {
      output += alphabet[(alphabet.indexOf(initial[i]) + shift + 26) % 26];
    } else {
      output += initial[i];
    }
  }
  inps[2].value(output);
}

function decrypt() {
  const initial = inps[0].value().toUpperCase();
  const shift = int(inps[1].value());
  let output = '';
  for (let i = 0; i < initial.length; i++) {
    if (alphabet.includes(initial[i])) {
      output += alphabet[(alphabet.indexOf(initial[i]) - shift + 26) % 26];
    } else {
      output += initial[i];
    }
  }
  inps[2].value(output);
}