My test string:
/custom-heads/food-drinks/51374-easter-bunny-cake
I am trying to capture the number in the string. The constants in that string are the the number is always preceded by 3 /'s and followed by a -.
I am a regex noob and am struggling with this. I cobbled together (\/)(.*?)(-) and then figured I could get the last one programmatically, but I would really like to understand regex better and would love if someone could show me the regex to get the last occurrence of numbers between / and -.
Don't use regexes if possible, i reccomend you to read - https://blog.codinghorror.com/regular-expressions-now-you-have-two-problems/ blog post
To your question, its easier, faster, more bullet proof to get it using splits
const articleName = "/custom-heads/food-drinks/51374-easter-bunny-cake".split("/")[3]
// '51374-easter-bunny-cake'
const articleId = articleName.split("-")[0]
// '51374'
hope it helps
You may use this regex with a capture group:
^(?:[^\/]*\/){3}([^-]+)
Or in modern browsers you can use lookbehind assertion:
/(?<=^(?:[^\/]*\/){3})[^-]+/
RegEx Code:
^: Start(?:[^\/]*\/){3}: Match 0 or more non-/ characters followed by a /. Repeat this group 3 times([^-]+): Match 1+ of non-hyphen charactersCode:
const s = `/custom-heads/food-drinks/51374-easter-bunny-cake`;
const re = /^(?:[^\/]*\/){3}([^-]+)/;
console.log (s.match(re)[1]);Use
const str = `/custom-heads/food-drinks/51374-easter-bunny-cake`
const p = /(?:\/[^\/]*){2}\/(\d+)-/
console.log(str.match(p)?.[1])See regex proof.
EXPLANATION
Non-capturing group (?:\/[^\/]*){2}
{2} matches the previous token exactly 2 times
\/ matches the character / with index 4710 (2F16 or 578) literally (case sensitive)
Match a single character not present in the list below [^\/]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\/ matches the character / with index 4710 (2F16 or 578) literally (case sensitive)
\/ matches the character / with index 4710 (2F16 or 578) literally (case sensitive)
1st Capturing Group (\d+)
\d matches a digit (equivalent to [0-9])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)