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

Here's my modification of this post which was for changing to Title Case.

You could immediately toLowerCase the string, and then just toUpperCase the first letter of each word. Becomes a very simple 1 liner:

Instead of making it every word. This example is compatible with multiple lines and strings like A.M. and P.M. and of course, any word proceeding a period and a whitespace character.

You could add your own custom words below that toLowerCaseNames function and toUpperCaseNames in that example below.

// Based off this post: https://stackoverflow.com/a/40111894/8262102
var str = '-------------------\nhello world!\n\n2 Line Breaks. What is going on with this string. L.M.A.O.\n\nThee End...\nlower case example 1\nlower case example 2\n-------------------\nwait there\'s more!\n-------------------\nhi all, this is derp. thank you all to answer my query.';
function toTitleCase(str) {
 return str.toLowerCase().replace(/\.\s*([a-z])|^[a-z]/gm, s => s.toUpperCase());
}

// Add your own names here to override to lower case
function toLowerCaseNames(str) {
  return str.replace(/\b(lower case example 1|lower case example 2)\b/gmi, s => s.toLowerCase());
}

// Add your own names here to override to UPPER CASE
function toUpperCaseNames(str) {
  return str.replace(/\b(hello|string)\b/gmi, s => s.toUpperCase());
}

console.log(toLowerCaseNames(toUpperCaseNames(toTitleCase(str))));

---

You can paste all those regexp above into https://regexr.com/ to break down how they work.

Answer 2

This is the solution I ended up using:

str = 'hi all, this is derp. thank you all to answer my query.';
temp_arr = str.split('.');
for (i = 0; i < temp_arr.length; i++) {
temp_arr[i]=temp_arr[i].trim()
temp_arr[i] = temp_arr[i].charAt(0).toUpperCase() + temp_arr[i].substr(1).toLowerCase();
}
str=temp_arr.join('. ') + '.';
return str;

Answer 3

The below code is working for me as expected.

   function toSentenceCase(inputString) {
        inputString = "." + inputString;
   var result = "";
   if (inputString.length == 0) {
       return result;
   }

   var terminalCharacterEncountered = false;
   var terminalCharacters = [".", "?", "!"];
   for (var i = 0; i < inputString.length; i++) {
       var currentChar = inputString.charAt(i);
       if (terminalCharacterEncountered) {
           if (currentChar == ' ') {
               result = result + currentChar;
           } else {
               var currentCharToUpperCase = currentChar.toUpperCase();
               result = result + currentCharToUpperCase;
               terminalCharacterEncountered = false;
           }
       } else {
           var currentCharToLowerCase = currentChar.toLowerCase();
           result = result + currentCharToLowerCase;
       }
       for (var j = 0; j < terminalCharacters.length; j++) {
           if (currentChar == terminalCharacters[j]) {
               terminalCharacterEncountered = true;
               break;
           }
       }
   }
        result = result.substring(1, result.length - 1);
   return result;
 }

Answer 4

Try this, It will work fine for you. It will also work for String having leading spaces.

var string="hi all, this is derp. thank you all to answer my query.";
var n=string.split(".");
var vfinal=""
for(i=0;i<n.length;i++)
{
   var spaceput=""
   var spaceCount=n[i].replace(/^(\s*).*$/,"$1").length;
   n[i]=n[i].replace(/^\s+/,"");
   var newstring=n[i].charAt(n[i]).toUpperCase() + n[i].slice(1);
   for(j=0;j<spaceCount;j++)
   spaceput=spaceput+" ";
   vfinal=vfinal+spaceput+newstring+".";
 }
 vfinal=vfinal.substring(0, vfinal.length - 1);
 alert(vfinal);