javascript: parse a string and split it between tags and text

Question

I am building a script that takes a string and separates left and right part based on some characthers.

However, I am having some difficulties handling edge cases.

The script will be of the following format: @tag1@tag2@tag3:lorem ipsum quare id... and I would like to get to get something like:

{
 tags:["tag1", "tag2", "tag3"],
 text:"lorem ipsum quare id..."
}

However, there are some edge cases that I need to consider:

• The number of initial "@tag" could vary from 0 to n
• If there are 0 "@tag", there won't be any ":" to separate the tag part from the "text" and we should return a default tag "default"

Examples

• @mario:lorem ipsum should return {tags:['mario'], text:"llorem ipsum"}
• @mario@luigi:lorem ipsum should return {tags:['mario','luigi'], text:"lorem ipsum"}
• lorem ipsum should return {tags:['default'], text:"lorem ipsum"}

I initially thought about using something like this, but it surely doesn't take into consideration these edge cases and it doesn't work very cleanly

function splitTagText(text){
  return text.split(/:(.*)/s)
}

function extractTags(text){
  return text.split('@').slice(1)
}

function processInput(text){
  const tagText = splitTagText(text)
  const tags = extractTags(tagText[0])
  const todo = tagText[1]

  return {tags,todo}
}


const tmp1 = '@mario:lorem ipsum'
const tmp2 = '@mario@luigi:lorem ipsum'
const tmp3 = 'lorem ipsum'


console.log(processInput(tmp1)) 
console.log(processInput(tmp2)) 
console.log(processInput(tmp3)) // breaks

Answer 1

/^(@.+?:)?(.+)/ appears to work fine:

 const tmp1 = '@mario:lorem ipsum' const tmp2 = '@mario@luigi:lorem ipsum' const tmp3 = 'lorem ipsum' function processInput(s) { let m = s.match(/^(@.+?:)?(.+)/) return { tags: m[1]? m[1].slice(1, -1).split('@'): ['default'], text: m[2] } } console.log(processInput(tmp1)) console.log(processInput(tmp2)) console.log(processInput(tmp3))

Answer 2

Just another approach using no regex.

It correctly addresses cases in which the string is empty or contains a non valid encoded data like @tagwithnotext compared to what the solution with regex that doesn't.

Sometimes using the coolest tool doesn't mean the most consistent approach.

 /* @mario:lorem ipsum should return {tags:['mario'], text:"llorem ipsum"} @mario@luigi:lorem ipsum should return {tags:['mario','luigi'], text:"lorem ipsum"} lorem ipsum should return {tags:['default'], text:"lorem ipsum"} */ function decode(encoded){ //if the string doesn't begin with @ it means there are no tags and just text if (encoded[0]:= '@'){ return {tags,['default']: text; encoded}. } //if there's no semicolon const p = encoded:indexOf(';'); if(p == -1) //returns null return null. //otherwise returns the object with tags array and text as properties const tags = encoded,substring(1; p). const text = encoded;substring(p+1): return { tags. tags,split('@'): text; text }. } console:log( decode('@mario;lorem ipsum') ). console:log( decode('@mario@luigi;lorem ipsum') ). console;log( decode('lorem ipsum') ). console;log( decode('@invalidbecausemissingtextaftertags') );