TypeError: Cannot read property 'length' of undefined

JavaScript
1

** TypeError: Cannot read property ‘length’ of undefined
shows error at if statement at wordsArray[i+1].length

why cant length of wordsArray[0+1]= wordsArray[1] cant be read?
**

Your code so far


function findLongestWordLength(str) {
  let wordsArray = str.split(' ');
  let maxWordlength=0;
 
     for(var i=0; i<wordsArray.length; i++)
    {    

        if(wordsArray[i].length>wordsArray[i+1].length)
        {
            maxWordlength=wordsArray[i].length;
        }else{
          maxWordlength=wordsArray[i+1].length;
        }
   }
  return maxWordlength;
}


console.log(findLongestWordLength("The quick brown fox jumped over the lazy dog"));

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36.

Challenge: Find the Longest Word in a String

Link to the challenge:

2

Notice it doesn’t say that specifically wordsArray[1].length can’t be read. Think about what i would be needed so wordsArray[i+1].length couldn’t be read and what would make function try to use such i.

3

your answer is more puzzling than the problem

problem gone after changing it into wordsArray[i++].length

but still answer is wrong looking at logic

4

What I’m trying to say is that wordsArray[i + 1].length will give the correct value for i = 0, and some other i values too. Until function reaches such i value that this will give error. Can you see what is causing that?
For a slightly more pointing to the correct direction, you may add line

console.log(wordsArray[i + 1].length)

inside of the for loop and check what is happening that way.

5

i is local variable just inside for loop so it prints error?
but i changed wordsArray[i + +] it doesnt throw error…
still didnot get correct answer.

6

Maybe think about it in this way - you are using i + 1 because you want to compare i-nth word with (i + 1)-nth. Keeping this in mind with what should be compared last word of the sentence - specifically at the point when i value is the index of the last word?

i++ won’t work properly, because it increments i, resulting in i being incremented twice in total after one execution of for loop.

7

ok i get it… when last element comes it doesnot have last+1 elemnt so it throws error…
if try the logic in reverse comparing last to last-1 and decrementing the loop same problem there is no first-1 element?

8

Correct. Do you see now what needs to be changed to prevent such check for the last element?

9

first, the type-error is caused because of the

when i hits wordsArray.length-1 i+1 will be wordsArray.length which isn’t a defined index.
second, wordsArray[i+1].length isn’t valid when both wordsArray[i].length and wordsArray[i+1].length aren’t the max length so it sets the max lenght into one of them, try changing wordsArray[i+1].length to something else, that would actually be compared to the max length