How do I split a value using the split function from javascript to split checking only the first and last occurence

Question

So I need to split an regex that's coming from my database. The value is like the following

regexValue = '/^([0-9]{3}\.?[0-9]{3}\.?[0-9]{3}\-?[0-9]{2}|[0-9]{2}\.?[0-9]{3}\.?[0-9]{3}\/?[0-9]{4}\-?[0-9]{2})$/ig'

if you analyze throughly this regex you can see that it have an forward slash '/' between the regex. So if I wanted to split it, using

values.split('/'); 

It would generate more strings than I would like to. For example a simple regex

//would generate three values("", \w+ , ig)    
regexValue = '/\w+/ig'
regexValue.split('/');

Is there a way so I could only split getting the first and last values?

Answer 1

If you want to split that string into the regular expression bodyand its flags, you can do that easily with...a regular expression. 😃

const parts = /^\s*\/(.*)\/(?:([a-z]*))\s*$/.exec(regexString);
//           A ^
//           B  ^^^
//           C     ^^
//           D       ^^^^
//           E           ^^
//           F             ^^^^^^^^^^^^
//           G                         ^^^
//           H                            ^

• A: Start of input
• B: Optional whitespace
• C: Leading slash of regex "literal"
• D: Body of the expression
• E: Ending slash of regex "literal"
• F: Optional flags
• G: Optional whitespace
• H: End of input

Live Example:

 const regexString = '/^([0-9]{3}\\\\.?[0-9]{3}\\\\.?[0-9]{3}\\\\-?[0-9]{2}|[0-9]{2}\\\\.?[0-9]{3}\\\\.?[0-9]{3}\\\\/?[0-9]{4}\\\\-?[0-9]{2})$/ig'; const parts = /^\\s*\\/(.*)\\/(?:([az]*))\\s*$/.exec(regexString); if (!parts) { console.log("No match"); } else { const [, body, flags] = parts; console.log(`body: ${body}`); console.log(`flags: ${flags}`); }

---

Note that I escaped the backslashes in the string literal, since you said you're reading this from your database, you don't have it in a string literal in your code. It's just that inside a string literal, a backslash is an escape character, so \\. and . mean exactly the same thing. To write a string literal defining a string with backslashes in it, you have to escape them as I've done in the snippet above. Again, you've said it comes from your database, so you're fine, but I figured I should escape them in the example to avoid being misleading.