// 檢驗手機號是否合格
      await this.$refs.form.validate("mobile");

rules: {
        mobile: [
          // 必填
          { required: true, message: "請?zhí)顚懹脩裘? },
          // 1  3-9  開頭  在家 9 個0-9數(shù)字
          { pattern: /^1[3-9]\d{9}$/, message: "手機號不正確" },
        ],
        code: [
          { required: true, message: "請?zhí)顚懨艽a" },
          { pattern: /\d{6}$/, message: "驗證碼錯誤" },
        ],
      },

<van-field
        v-model="user.mobile"
        name="mobile"
        icon-prefix="zlx"
        left-icon="shouji"
        maxlength="11"
        placeholder="請輸入手機號"
        :rules="rules.mobile"
      />

<van-field v-model="location" name="location" label="地點" placeholder="請輸入出差地" :rules="[{ required: true, pattern: /^\S{1,7}$/g, message: '請輸入7個以內字符' }]" />

watch: {
    location(val) {
      if (val.replace(/\s/g, '').length > 7) {
      	// 添加錯誤處理
      	// ....
        Toast.fail('長度超出')
        this.locationError = true
      } else {
        this.locationError = false
      }
    }
}

<van-field v-model="location" name="location" label="地點" placeholder="請輸入出差地" :rules="[{ required: true, validator, message: '請輸入7個以內字符' }]" />

validator(val) {
	return val.replace(/\s/g, '').length > 7 ? false : true
}