html;
 

 <span
                class="code"
                :style="{'color':codeColor}"
                @click="createCode(4)"
              >{{from.checkCode}}</span>

data:

 data() {
    return {
     
      codeColor: ""
    };
  },

  randomColor() {
      let R = Math.floor(Math.random() * 255);
      let G = Math.floor(Math.random() * 255);
      let B = Math.floor(Math.random() * 255);
      console.log("rgb(" + R + "," + G + "," + B + ")");
      this.codeColor = "rgb(" + R + "," + G + "," + B + ")";
    }