Explanation:

You have to go through each word and figure out which one is the longest and return not the word, but how many characters it has.

Hint: 1

You should split the string into an array of words.

Hint: 2

You will need to figure out a way to keep track globally of the greatest current length.

Hint: 3

Remember how to get the length of elements on the array? Array[index].length

Spoiler Alert!

Solution ahead!

Code Solution:

First solution

function findLongestWord(str) {
  var words = str.split(' ');
  var maxLength = 0;

  for (var i = 0; i < words.length; i++) {
    if (words[i].length > maxLength) {
      maxLength = words[i].length;
    }
  }

  return maxLength;
}

Second solution

(Using .reduce())

function findLongestWord(s) {
  return s.split(' ')
          .reduce(function(x,y) {
                    return Math.max(x, y.length)
                  }, 0);
}

Third solution

(Using recursiveness)

function findLongestWord(str) {

  //split the string into individual words 
  //(important!!, you'll see why later)
  str = str.split(" ");

  //str only has 1 element left that is the longest element, 
  //return the length of that element
  if(str.length == 1){
    return str[0].length;
  }

  //if the first element's length is greater than the second element's (or equal) 
  //remove the second element and recursively call the function)
  if(str[0].length >= str[1].length){
    str.splice(1,1);
    return findLongestWord(str.join(" "));
  }

  //if the second element's length is greater thant the first element's start 
  //call the function past the first element 
  if(str[0].length <= str[1].length){
    // from the first element to the last element inclusive.
    return findLongestWord(str.slice(1,str.length).join(" "));
  }
}

Code Explanation:

First solution

Take the string and convert it into an array of words. Declare a variable to keep track of the maximum length and loop from 0 to the length of the array of words.

Then check for the longest word by comparing the current word to the previous one and storing the new longest word. At the end of the loop just return the number value of the variable maxLength.

Second solution

For more information on reduce click here.
In case you're wondering about that 0 after the callback function, it is used to give an initial value to the x, so that Math.max will know where to start.

Third solution

See the code's inline comments.

Credits:

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