I am trying to detect all usernames following this form:
/@[a-zA-Z0-9_.-]{3,30}/
For example, in the following string
@eminem is singing with @rihanna
, the method must return
["@eminem", "@rihanna"]
I have tried the following:
function matchAllUsernames(str) {
const pattern = /@[a-zA-Z0-9_.-]{3,30}/g;
return [...str.matchAll(pattern)].flat();
}
const str = "@eminem is singing with @rihanna";
console.log(matchAllUsernames(str));But... what if I try with this string?
@eminem@ndsoiosd is singing with @rihanna
In this case, the method must ignore @eminem and @ndsoiosd, because there is no sparation between them...
function matchAllUsernames(str) {
const pattern = /@[a-zA-Z0-9_.-]{3,30}/g;
return [...str.matchAll(pattern)].flat();
}
const str = "@eminem@ndodshuoc is singing with @rihanna";
console.log(matchAllUsernames(str));How can I do that?
You can prepend an anchor for a non word boundary before the @ and assert a whitespace boundary to the right at the end of the pattern:
\B@[a-zA-Z0-9_.-]{3,30}(?!\S)
function matchAllUsernames(str) {
const pattern = /\B@[a-zA-Z0-9_.-]{3,30}(?!\S)/g;
return [...str.matchAll(pattern)].flat();
}
const str = "@eminem@ndodshuoc is singing with @rihanna";
console.log(matchAllUsernames(str));To support also the characters . and - not being allowed before the next @ sign:
(?<!\S)@[a-zA-Z0-9_.-]{3,30}(?!\S)
You can match consecutive mentions and discard those matches and only extract mentions from other contexts:
function matchAllUsernames(str) {
const pattern = /(?:@[\w.-]{3,30}){2,}|(@[\w.-]{3,30})/g;
return Array.from(str.matchAll(pattern), x=>x[1]).filter(Boolean);
}
const str = "@sia@ndodshuoc and @eminem are singing with @rihanna";
console.log(matchAllUsernames(str));Note that [A-Za-z0-9_] is equal to \w.
The (?:@[\w.-]{3,30}){2,}|(@[\w.-]{3,30}) regex matches two or more sequences of 3 to 30 word, . or - chars, or captures into Group 1 a sequence of 3 to 30 word, . or - chars (in another context).