lineBreak.js

function getSpacePositions(str, origin) {
  const positions = [];
  const pre = str.lastIndexOf(' ', origin);
  const post = str.indexOf(' ', origin);
  if (pre > 0) { positions.push(pre); }
  if (post > 0) { positions.push(post); }
  return positions;
}

function getClosestValue(positions, value) {
  return value - positions[0] < positions[1] - value ? positions[0] : positions[1];
}

function insertLineBreak(str, positions) {
  if (!positions.length) { return str; }
  let broken = str;
  positions.sort().forEach(function (position, index) {
    const positiom = position + index;
    broken = broken.substr(0, positiom).trim() + '\n' + broken.substr(positiom).trim();
  });
  return broken;
}

function getBreakForPosition(str, position) {
  const possibleBreaks = getSpacePositions(str, position);
  let bestPosition = 0;
  if (possibleBreaks.length == 1) {
    bestPosition = possibleBreaks[0];
  } else if (possibleBreaks.length > 1) {
    bestPosition = getClosestValue(possibleBreaks, position);
  }
  return bestPosition;
}

function getPositions(str, n) {
  const distance = str.length / n;
  const positions = [];
  const length = n - 1;
  for(let i = 1; i <= length; i++) {
    positions.push(distance * i);
  }
  return positions;
}

function insertLineBreaks(str) {
  const positions = getPositions(str, 3);
  const bestPositions = positions.map(function(position) {
    return getBreakForPosition(str, position);
  })
  return insertLineBreak(str, bestPositions);
}

console.log(insertLineBreaks('Mario Vargass Lsssssosa Vargass'));
console.log(insertLineBreaks('M a r i o V a r g a s    s Lsssssosa Vargass'));