element-ui校验表单项为数字校验

html页面部分

<el-form ref="form" :model="form" label-width="200px">
  <el-form-item prop="num">
    <el-input v-model="form.num" ></el-input>
  </el-form-item>
</el-form>

js实现部分 

export default {
  data() {
    var checkNum = (rule, value, callback) => {
      console.log("value", value - 0);
      if (isNaN(value)) {
        return callback("请输入数字");
      }
      return callback();
    },
    return {
      rules:{
        num: [
          { required: true, message: "请输入数字", trigger: "blur" },
          { validator: checkNum, trigger: "blur"}
        ]
      }
    }
  }
}