Find the longest word in a string help please

Find the longest word in a string help please
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Good morning fellow coders! Can someone please tell me what is wrong with my code? Or at least give me a hint? I keep getting “TypeError: Cannot read property ‘length’ of undefined. :confused: The following is my code:
function findLongestWord(str) {
var longestSoFar = 0;
str.split(” ");

for (var i = 0; i < str.length; i++) {
if (str[i].length > str[i + 1].length) {
longestSoFar = str[i].length;
else if (str[i].length < str[i + 1].length) {
longestSoFar = str[i + 1].length;

return longestSoFar;


I’ll drop a few hints before I go to sleep (it’s already midnight here and I can’t stay awake any longer)

.split() returns a new array. It doesn’t modify str in-place (or any string function for that matter).

Check what you’re comparing against. For every word in the string, is this word longer than the current longest word?


Awesome! Thank you so much!


Here’s my solution :

function findLongestWord(str) {
var wordArr = str.split(" ");

var longestWord = 0;

for (var i = 0; i < wordArr.length; i++) {
if (wordArr[i].length > longestWord) {
longestWord = wordArr[i].length;
return longestWord;

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

However at first i was having problem in the “for loop”. my code was:

for (var i = 0; i <= wordArr.length; i++)

that equal sign was making all the difference. but I’m still not sure what was wrong with the equal sign! I think its something simple but i don’t get it. So, can someone please help me understand this.


Let’s take an array of words wordArr = ['alfa', 'beta', 'charly'];

When you have

for (var i = 0; i <= wordArr.length; i++)

and the loop reaches the last element

i = wordArr.length

what will wordArr[i] be?


ah! got it! thanks so much. it was simply - but i got confused !!! the equal sign was taking it to one extra mile!!! :slight_smile: