Returning the length of largest word in a sentence [duplicate]

Question

I have written a function which receives a sentence and calculates the longest word in that sentence.

function findLongestWord(str) {

  var charArray = str.split(" ");
  var wordArray = [];


  for(var i = 0; i < charArray.length; i++ ) {
    wordArray.push(charArray[i].length);
    wordArray.sort();
    wordArray.reverse();

  }

  return wordArray[0];
}

My function works with inputs such as:

findLongestWord("The quick brown fox jumped over the lazy dog");

But when i pass it:

findLongestWord("What if we try a super-long word such as otorhinolaryngology")

The function returns:

4

Rather than

19

Answer 1

Your sort function sorts the array lexically, so you end up with

[1,10,19,2,2,2,3,4,4,4]

reversing that, you get

[4,4,4,3,2,2,2,19,10,1]

where 4 is the first number

You don't need the sorting at all, just use Math.max instead

function findLongestWord(str) {
    return Math.max.apply( null, str.split(" ").map( (x) => x.length) );
}

Answer 2

TL;DR

Your numbers are getting sorted as strings.

To get them sorted as numbers, in descending order, in your function you should instead do:

wordArray.sort(function(a, b) { return b - a; });

EXPLANATION

According to the docs:

The sort() method sorts the elements of an array in place and returns the array. The sort is not necessarily stable. The default sort order is according to string Unicode code points.

[...]

Syntax

arr.sort()

arr.sort(compareFunction)

Parameters

compareFunction Optional

Specifies a function that defines the sort order. If omitted, the array is sorted according to each character's Unicode code point value, according to the string conversion of each element.

Emphasis mine, so you end up with something like this:

var str = "What if we try a super-long word such as otorhinolaryngology";
var charArray = str.split(" ");
// now charArray == ["What", "if", "we", "try", "a", "super-long", "word", "such", "as", "otorhinolaryngology"]
// when you take the length of each word and end up with
var wordArray = [4, 2, 2, 3, 1, 10, 4, 4, 2, 19];
// and if you use plain wordArray.sort() without specific sort function you get
wordArray = [1, 10, 19, 2, 2, 2, 3, 4, 4, 4];
// and once reversed it is
wordArray = [4, 4, 4, 3, 2, 2, 2, 19, 10, 1];
// this is why you end up with wordArray[0] == 4

You could also implement the whole function as a one-liner:

function findLongestWord(str) {
  return str.split(/\s+/).sort(function(a, b) { return b.length - a.length; })[0].length;
}

console.log("Longest word length = ", findLongestWord("The default sort order is according to string Unicode code points"));

console.log("Longest word length = ", findLongestWord("What if we try a super-long word such as otorhinolaryngology"));