Looking for possible regex solution, since I still suck at it. The goal of the regex is to validate if string fits the format. 
First should be random length string, then comes colon (`:`) and the last is one of two options: `desc` or `asc`. 

`someString:desc|asc`
Examples: `firstName:desc`, `lastName:asc`

@venus have you tried with `/\w+:(desc|asc)/`?

You can play with it on https://regex101.com/r/EcV8bn/1

Looks good to me, thanks. But when I add some string after `desc` or `asc` it will still return true value:

```js
console.log({ matched: Boolean(/\w+:(desc|asc)/.test("firstName:desca")) });
```

You can make regex to check for end of string after `desc|asc` via `$`