Question

124

How to fix TypeError: Cannot read property 'length' of undefined in JavaScript?

rated 0 times [ 127] [ 3] / answers: 1 / hits: 12820 / 5 Years ago, mon, october 21, 2019, 12:00:00

I am trying to solve a very easy challenge about finding the longest word in a string.
This is the code:

function find(par) {

    let arrayWord = par.split( );

    let longestWord = ;

    for (let i = 0; i <= arrayWord.length; i++) {

        if (longestWord.length < arrayWord[i].length) {

            longestWord = arrayWord[i]

        }

    }

    return longestWord;

}

find(Find the longest word);

I would need help understanding why I am getting this error:

Uncaught TypeError: Cannot read property 'length' of undefined
at find (:5:47)
at :11:1 find @ VM959:5 (anonymous) @ VM959:11

thank you.

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jarod

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answered 5 Years ago gonzaloulyssess · Accepted Answer

Cannot read property 'length' of undefined comes when it is not able to find variable of certain type(In your case a string) to call the function length. In your case arrayWord[i].length is not a proper string for the last condition of your check as there is no element arrayWord[arrayWord.length] present in the array. That's why arrayWord[i].length is giving you an error for your last iteration. Just change i <= arrayWord.length to i < arrayWord.length

function find(par) {

  let arrayWord = par.split( );

  let longestWord = ;

  for (let i = 0; i <arrayWord.length; i++) {

    if (longestWord.length < arrayWord[i].length) {

      longestWord = arrayWord[i]

    }

  }

  return longestWord;

}

Edits: Changes made as suggested by RobG