vue 表单校验不通过时拦截提交表单

上代码：

<el-form :model="ruleForm" :rules="rules" ref="ruleForm" label-width="100px" class="demo-ruleForm">
  <el-form-item label="名称" prop="name">
    <el-input type="textarea" v-model="ruleForm.name"></el-input>
  </el-form-item>
  <el-form-item>
    <el-button type="primary" @click="submitForm('ruleForm')">立即创建</el-button>
  </el-form-item>
</el-form>
<script>
  export default {
    data() {
      return {
        ruleForm: {
          name: ''
        },
        rules: {
          name: [
            { required: true, message: '请输入活动名称', trigger: 'blur' },
            { min: 3, max: 5, message: '长度在 3 到 5 个字符', trigger: 'blur' }
          ]
        }
      };
    },
    methods: {
      submitForm(formName) {
        this.$refs[formName].validate((valid) => {  //开启校验
          if (valid) {   // 如果校验通过，请求接口，允许提交表单
            alert('submit!');
          } else {   //校验不通过
            return false;
          }
        });
      }
    }
  }
</script>