Cannot Read Property 'render' of Undefined Datetime.js

If you've e'er used JavaScript'due south split method, there's a good adventure that you've encountered the following error: TypeError: Cannot read property 'separate' of undefined.

There are a few reasons why you would receive this error. Most probable information technology's just a basic misunderstanding of how split works and how to iterate through arrays.

For example, if y'all endeavour to submit the following code for the Find the Longest Word in a String challenge:

                part findLongestWord(str) {    for(let i = 0; i < str.length; i++) {     const array = str.divide(" ");     array[i].split("");   } }  findLongestWord("The quick brown fox jumped over the lazy dog");              

it volition throw the TypeError: Cannot read property 'split' of undefined error.

The split method

When split is called on a string, it splits the string into substrings based on the separator passed in as an statement. If an empty string is passed as an argument, dissever treats each character as a substring. It so returns an array containing the substrings:

                const testStr1 = "Test exam ane 2"; const testStr2 = "cupcake pancake"; const testStr3 = "Start,2d,Third";  testStr1.carve up(" "); // [ 'Test', 'test', '1', 'ii' ] testStr2.split(""); // [ 'c', 'u', 'p', 'c', 'a', 'one thousand', 'eastward', ' ', 'p', 'a', 'n', 'c', 'a', 'one thousand', 'e' ] testStr3.split up(","); // [ 'First', 'Second', 'Tertiary' ]                              

Check out MDN for more details about split.

The problem explained with examples

Knowing what the split method returns and how many substrings you can look is the key to solving this challenge.

Allow's take another wait at the code to a higher place and see why it's non working equally expected:

                function findLongestWord(str) {    for(let i = 0; i < str.length; i++) {     const array = str.split(" ");     array[i].separate("");   } }  findLongestWord("The quick dark-brown play a joke on jumped over the lazy dog");                              

Splitting str into an array like this (const array = str.carve up(" ");) works as expected and returns [ 'The',   'quick',   'dark-brown',   'play a joke on',   'jumped',   'over',   'the',   'lazy',   'domestic dog' ].

Just take a closer look at the for loop. Rather than using the length of array as a condition to iterate i, str.length is used instead.

str is "The quick brown fox jumped over the lazy dog", and if you log str.length to the panel, you'll get 44.

The last statement in the body of the for loop is what's causing the fault: assortment[i].divide("");. The length of array is 9, so i would quickly go way over the maximum length of assortment:

                part findLongestWord(str) {    for(allow i = 0; i < str.length; i++) {     const assortment = str.split(" ");     console.log(assortment[i]);     // array[0]: "The"     // assortment[1]: "quick"     // array[2]: "dark-brown"     // ...     // array[9]: "dog"     // array[10]: undefined     // array[11]: undefined   } }  findLongestWord("The quick brown fox jumped over the lazy dog");                              

Calling assortment[i].dissever(""); to split each string into substrings of characters is a valid approach, but it volition throw TypeError: Cannot read property 'divide' of undefined when it's passed undefined.

How to solve Detect the Longest Discussion in a String with split

Let'southward apace go over some pseudo code for how to solve this problem:

1. Split str into an array of individual words
2. Create a variable to track the greatest give-and-take length
3. Iterate through the array of words and compare the length of each word to the variable mentioned above
4. If the length of the electric current word is greater than the one stored in the variable, replace that value with the current word length
5. Once the length of every word is compared with the maximum discussion length variable, render that number from the office

First, divide str into an array of individual words:

                role findLongestWordLength(str) {   const array = str.split(" "); }              

Create a variable to keep track of the longest give-and-take length and set information technology to zero:

                function findLongestWordLength(str) {   const assortment = str.dissever(" ");   let maxWordLength = 0; }              

Now that the value of array is ['The', 'quick', 'brown', 'fox', 'jumped', 'over', 'the', 'lazy', 'domestic dog'], you can use array.length in your for loop:

                function findLongestWordLength(str) {   const array = str.divide(" ");   let maxWordLength = 0;      for (permit i = 0; i < array.length; i++) {        } }              

Iterate through the array of words and check the length of each word. Remember that strings also have a length method you lot tin call to hands get the length of a string:

                function findLongestWordLength(str) {   const assortment = str.split(" ");   let maxLength = 0;      for (allow i = 0; i < array.length; i++) {     assortment[i].length;   } }              

Apply an if statement check if the length of the current give-and-take (assortment[i].length) is greater than maxLength. If and then, supercede the value of maxLength with assortment[i].length:

                function findLongestWordLength(str) {   const array = str.divide(" ");   let maxLength = 0;      for (let i = 0; i < array.length; i++) {     if (array[i].length > maxLength) {       maxLength = array[i].length;     }   } }              

Finally, render maxLength at the cease of the function, after the for loop:

                function findLongestWordLength(str) {   const assortment = str.divide(" ");   let maxLength = 0;      for (permit i = 0; i < array.length; i++) {     if (array[i].length > maxLength) {       maxLength = array[i].length;     }   }        return maxLength; }              

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Source: https://www.freecodecamp.org/news/cannot-read-property-split-of-undefined-error/

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