Shadowing Practice: Array Map in 100 Seconds - Learn English Speaking with Video
Creating lesson...
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ArrayMap.
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Create a new array by calling a function on every element in a different array.
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Imagine we have an array of squares.
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We can call a function on every single one of those
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squares using map to convert it to a new array of circles.
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In other words, it's just a loop, where the goal of that loop is to create a new array.
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In our code, let's start with an array of objects that contain some user data.
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Our goal is to take this array of objects
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and convert it to an array of strings that only contain the user names.
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You could do this imperatively by creating a new empty array, then use a for loop to push each individual username to the new array.
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Notice how we're using statements to change the app's state.
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This is known as imperative programming.
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Map on the other hand is declarative and describes how to create this new array using a function.
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The new array is equal to the original array mapped to a function.
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The function is passed as an argument to map, and it's called on every element in the original array.
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The function has access to the current element in the loop as well as its index.
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In the body of the function, your job is to compute a new value and then return it.
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And we've now solved the same problem we did with the for loop, but with less code and without mutating the internal state.
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If you're a ReactJS user, you'll often see Map used to take some initial data and then map it to JSX for the actual UI.
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Or maybe you need these usernames to do something asynchronously like fetch additional data from the database.
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You could do that by mapping them all to an array of promises, then running them concurrently with promise.all.
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One anti-pattern to be aware of with map is
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that you should only use it if you plan on using the new array.
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If you just need to run a loop, consider for each, or a regular for loop instead.
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This has been ArrayMap in 100 seconds, thanks for watching, and I will see you in the next one.
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About This Lesson
You're practicing English with "Array Map in 100 Seconds" using the Shadowing technique — a method originally developed for professional interpreter training.
Focus on sounding like the speaker — not just repeating words. With 15–30 minutes of daily practice, you'll build real-world speaking confidence.
What is the Shadowing Technique?
Shadowing is a science-backed language learning technique originally developed for professional interpreter training and popularized by polyglot Dr. Alexander Arguelles. The method is simple but powerful: you listen to native English audio and immediately repeat it out loud — like a shadow following the speaker with just a 1–2 second delay. Unlike passive listening or grammar drills, shadowing forces your brain and mouth muscles to simultaneously process and reproduce real speech patterns. Research shows it significantly improves pronunciation accuracy, intonation, rhythm, connected speech, listening comprehension, and speaking fluency — making it one of the most effective methods for IELTS Speaking preparation and real-world English communication.