Trim string by total number of characters, but round to nearest sentence (ceiling)

string-trim-to-sentence.js

const trimByCharToSentence = (text = "", chars = 0) => {
  // string is broken down into sentences;
  // this is done by splitting it into array between
  // the most common sentence-ending punctuation marks:
  // period, exclaimation, ellipsis and question mark;
  // if string consists of a single statement, make an array
  // anyways
  const sentences = text.match(/[^\.!…\?]+[\.!…\?]+/g) || [text]
  // store
  let result = ""
  // cycle through sentences array
  sentences.forEach(sentence => {
    // if the `result` store isn't long enough
    // add a sentence, until we're out of available
    // sentences
    if(result.length < chars) result += sentence
  })
  // return the trimmed sentence or empty string as default
  return result
}