I have a string from an input named 'text' and from this one, I would like to generate hashtags for a different field in my mongoose model:
req.body.tags = req.body.text
.split('#')
.map((tag) =>
tag.trim().replace(/ +/g, ' ').split(' ').join('-').toLowerCase()
)
.filter((tag) => tag.length !== 0)
The code above is almost perfect but every time, I press a comma it gets inserted as a hashtag(or part of it) which is something I'm trying to avoid as well, take a look into what I'm talking about:
{
"text": "Hola, mi nombre es Kevin y tu como te llamas? #random, #userundefined"
}
The text above is the data I insert via Postman and this is the output:
"tags": [
"hola,-mi-nombre-es-kevin-y-tu-como-te-llamas?",
"random,",
"userundefined"
],
What I would like to get is this:
"tags": [
"random",
"userundefined"
],
I just want to retrieve the words followed by a # and just that, I don't want the commas after it as shown in the random tag
matchAll should be usefull here...
The demo below is based on the documentation example. It returns an array of match arrays. In your case, you want the match[1] of each match, therefore the chained map.
let text = "Hola, mi nombre es Kevin y tu como te llamas? #random, #userundefined, #user-defined, #Grand_Father, #test123Four, #99startWithNumberIsWrong, #911, #Special!characters?"
let validHashtags = [...text
.toLowerCase()
.matchAll(/#(([a-z_]+)([\w_]+)?)/g)]
.map(match => match[1])
console.log(validHashtags)So that would be:
req.body.tags = [...req.body.text
.toLowerCase()
.matchAll(/#(([a-z_]+)([\w_]+)?)/g)]
.map(match => match[1])
I used a regular expression that complies with hashtag.org:
For the length and slangs, you simply should advise your users about it when they enter the text.
You might want to trim the commas off the ends of your tags after you split:
.map((tag) => {
let newTag = tag.trim().replace(/ +/g, ' ').split(' ').join('-').toLowerCase();
if (newTag.endsWith(',')) {
newTag = newTag.substring(0, newTag.length - 1);
}
return newTag;
})
EDIT: If you're trying to get rid of anything that isn't preceded by a hashtag, you need to do your split a little differently. I would recommend maybe looking for .indexOf('#') and using .substring() to remove anything up to that index, then do your split.
Well, you could play around with req.body.text in a slightly different way, now that I see you want to filter out the tags from full texts
working example
//you can declare this function outside of whatever web-server callback you have
function tagsFrom(text){ //function
var toReturn=[], i=0, hashtag=false
let isNumber=(n)=>Number(n).toString()==n //!isNaN(n) doesn't work properly
let isValidChar=(c)=>c=="_"?true:isNumber(c)||(c.toUpperCase()!=c.toLowerCase())
for(let c of text){
if(typeof toReturn[i]!="string"){toReturn[i]=""} //because I can't add a character to undefined
if(c=="#"){hashtag=true;continue} //hashtag found
if(isValidChar(c)&&hashtag){toReturn[i]+=c} //character of a hashtag word
else if(hashtag){hashtag=false;i++} //no longer the hashtag
}
return toReturn.filter(tag=>tag.length&&!isNumber(tag))
//no empty values and a tag can't be ONLY a number
}
var req={body:{text:"Hola, mi nombre es Kevin y tu como te llamas? #random, #userundefined #1 #spanish101 #, #1name ##underscore_test"}} //test variable
req.body.tags = tagsFrom(req.body.text) //usage
console.log(req.body.tags)MY EDIT: I parse hashtags based on this article about hashtags