手写方案

RGB 色值 To 十六进制色值

---

function setRGBTo16(str) {
  const reg = /^(rgb|RGB)/;
  if (!reg.test(str)) {
    return;
  }
  const arr = str.slice(4, str.length - 1).split(",");
  let color = "#";
  for (let i = 0; i < arr.length; i++) {
    let t = Number(arr[i]).toString(16);
    if (t.length < 2) {
      t = t + "0";
    }
    color += t;
  }
  return color;
}

十六进制色值 To RGB 色值

---

function set16ToRGB(str) {
  const reg = /^#([0-9A-Fa-f]{3}|[0-9A-Fa-f]{6})$/;
  if (!reg.test(str)) {
    return;
  }
  let newStr = str.toLowerCase().slice(1);
  let len = newStr.length;
  if (len === 3) {
    let t = "";
    for (let i = 0; i < len; i++) {
      t += newStr.slice(i, i + 1).concat(newStr.slice(i, i + 1));
    }
    newStr = t;
  }
  const arr = [];
  for (let i = 0; i < 6; i = i + 2) {
    let s = newStr.slice(i, i + 2);
    arr.push(parseInt("0x" + s));
  }
  return `rgb(${arr.join(",")})`;
}