Insert a line break at the best postition

lineBreak.js

function calcStandardDeviation(values){
  var avg = calcAverage(values);
  
  var squareDiffs = values.map(function(value){
    var diff = value - avg;
    var sqrDiff = diff * diff;
    return sqrDiff;
  });
  
  var avgSquareDiff = calcAverage(squareDiffs);

  var stdDev = Math.sqrt(avgSquareDiff);
  return stdDev;
}

function calcAverage(data){
  var sum = data.reduce(function(sum, value){
    return sum + value;
  }, 0);

  var avg = sum / data.length;
  return avg;
}

function countChunksLength(arr) {
  return arr.reduce(function(sum, n) {
    return sum + n.length;
  }, 0);
}

function countDifference(arr) {
  return calcStandardDeviation(arr);
}

function countPartsLength(parts, n) {
  const chunks = divideArray(parts, n);
  const sizes = _.map(chunks, chunk => {
    return countChunksLength(chunk);
  });
  return sizes;
}

function divideArray(arr, n) {
  const leftSide = _.clone(arr).splice(0, n);
  const rightSide = _.clone(arr).splice(n, arr.length - n);
  return [leftSide, rightSide];
};

function checkBreakPoint(parts, position) {
  const sizes = countPartsLength(parts, position);
  const difference = countDifference(sizes);
  return {
    [position]: difference,
  };
}

function countPossibleBreakPoints(parts) {
  const nParts = parts.length;
  return nParts - 1;
}

function getBestBreakPoints(arr) {
  return parseInt(_.keys(_.first(_.sortBy(arr, v => {
    return _.values(v)[0];
  })))[0]);
}

function insertLineBreak(parts, breakPoint) {
  return _.map(divideArray(parts, breakPoint), part => {
    return part.join(' ');
  }).join('\n');
}

function insertLineBreaks(str) {
  const parts = str.split(' ');
  const nPossibleBreaks = countPossibleBreakPoints(parts);
  const possibilities = _.times(nPossibleBreaks, n => {
    const position = n + 1;
    return checkBreakPoint(parts, position);
  })
  const bestBreakPoint = getBestBreakPoints(possibilities);
  return insertLineBreak(parts, bestBreakPoint)
}

console.log(insertLineBreaks('Yo Yo Ma'));
console.log(insertLineBreaks('Tim Berners-Lee'));
console.log(insertLineBreaks('Mario Vargas Llosa'));
console.log(insertLineBreaks('Edward O. Wilson'));
console.log(insertLineBreaks('Adolfo Perez Esquivel'));
console.log(insertLineBreaks('Marian Wright Edelman'));
console.log(insertLineBreaks('Hans Magnus Enzensberger'));
console.log(insertLineBreaks('King Jigme Singye Wangchuck'));
console.log(insertLineBreaks('Enrique Valentin Iglesias'));
console.log(insertLineBreaks('Jesús Silva Herzog Márquez'));