See [this at mozilla](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp)

## Case Insensitive
```javascript
const re = /ab+c/i; // literal notation
const re = new RegExp('ab+c', 'i'); // constructor with string pattern as first argument
const re = new RegExp(/aw/ab+c/, 'i'); // constructor with regular expression literal as first argument
```