自定义检验 正则表达式是否书写正确

      ruleRegexExpress: [
          {required: true, message: '请输入', trigger: 'blur'},
          {
            validator: (rule, value, callback) => {
          
              if (value !== undefined && value !== null) {
                let res = false
                try {
                  res = !!(eval(value) instanceof RegExp)
                } catch (err) {
                  res = false
                }
                if (!res) {
                  callback(new Error('请输入正确的正则表达式'))
                } else {
                  callback()
                }
              } else {
                callback()
              }
            },
            trigger: 'blur'
          }
        ],