Convert string to sentence case in javascript

Question

I want a string entered should be converted to sentence case in whatever case it is.

Like

hi all, this is derp. thank you all to answer my qu

Answer 1

The following SentenceCase code works fine for me and also handles abbreviations such e.g. a.m. and so on. May require improvements.

//=============================
// SentenceCase Function
// Copes with abbreviations
// Mohsen Alyafei (12-05-2017)
//=============================

function stringSentenceCase(str) {
  return str.replace(/\.\s+([a-z])[^\.]|^(\s*[a-z])[^\.]/g, s => s.replace(/([a-z])/,s => s.toUpperCase()))
}
//=============================

console.log(stringSentenceCase(" start sentence.   second sentence . e.g. a.m. p.m."))
console.log(stringSentenceCase("first sentence. second sentence."))
console.log(stringSentenceCase("e.g. a.m. p.m. P.M. another sentence"))