How to Create a LongestWord Function in JavaScript with Technical Explanation

Find the Longest Word in JavaScript with longestWord

Okay, so this time I want to share about a simple but quite interesting function that I came across while learning JavaScript and I found this on codewars. The function name is longestWord. As the name suggests, this function will search and return the longest word from a string.

I will explain why this function works, what methods are used, and the reasons. Come on, let's get straight to the detailed explanation!

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The purpose of the longestWord function

This function has a simple task: it accepts input in the form of a string containing several words (separated by spaces), then returns the longest word. If it turns out there is more than one word with the same length, this function will take the last word found.

An example is like this:

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Function Code

Here's the code, it's really short, but the cool thing is that behind the scenes there's a lot going on:

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Technical Explanation

1. Splitting a String into an Array of Words: .split(' ')

First, the entered string is split into an array of words with the split(' ') method. So the spaces in the string are like separators between words.

For example:

This is important because we cannot directly manipulate strings like arrays. With split, each word becomes an array element which is very easy to manage.

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2. Sorting Words By Length: .sort((a, b) => a.length - b.length)

After it is an array, we sort the words from shortest to longest using the sort method.

In sort, I give a callback (a, b) => a.length - b.length. Essentially, I'm asking JavaScript to sort the array elements by length.

The result?

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3. Take the Longest Word: .slice(-1)

Because the array is sorted, the longest word must be at the end of the array. So, the slice(-1) function is to take the last element.

An example is like this:

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4. Change it again to string: .toString()

The result of slice(-1) is actually still in the form of an array, even though it only contains one element. So that it matches the requested output, we convert it again to a string using toString().

Final result:

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Why Use These Methods?

1. split(' '): Because strings are immutable (can't be changed directly), I first split them into an array so it's easy to process.
2. sort(): The fastest way to find the largest or longest element is to sort the data first.
3. slice(-1): This is a simple trick to immediately grab the last element of the array.
4. toString(): Since the final output must be a string, this is the final step.

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For me, the longestWord function is like a good exercise to remember some important methods in JavaScript, especially for working with strings and arrays. From this function, I also understand more about how split, sort, slice and toString work.

If you have other ideas for solving this problem, or maybe you want further optimization, let's discuss together in the comments column! ?

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