颜色取一半

 hexToRGB(hex) {

      if (!/(^\#([a-fA-F0-9]{3})$)|(^\#([a-fA-F0-9]{6})$)/g.test(hex))

        return null;

      let allNumberStr = "0123456789abcdef"; // 十六进制的所有数字

      let len = hex.slice(1).length;

      let str =

        len === 6

          ? hex.slice(1)

          : hex.slice(1)[0].repeat(2) +

            hex.slice(1)[1].repeat(2) +

            hex.slice(1)[2].repeat(2);

      let arrStr = str.split("");

      let newArrStr = arrStr.map((item, index) => {

        return allNumberStr.indexOf((item + "").toLowerCase());

      });

      let num1 = newArrStr[0] * 16 + newArrStr[1];

      let num2 = newArrStr[2] * 16 + newArrStr[3];

      let num3 = newArrStr[4] * 16 + newArrStr[5];

      return `rgb(${num1}, ${num2}, ${num3}, 0.5)`;

    },