[рони]

Alexsandr,

"use strict"
const bigword = (str) => {
  let result = "";
  let b = true;
   for (let i = 0; i < str.length; i++){
    result += b ? str[i].toUpperCase() : str.charAt(i);
    b = str.charAt(i) === " ";}
    return result;
}
alert(bigword(" привет тест"));