JavaScript: Array Methods
Modern JavaScript is written with array methods, not for-loops. This quiz tests whether you know exactly what each one does — and which ones mutate your original array.
Questions cover map(), filter(), reduce(), forEach(), find(), some(), every(), slice(), and join() — including their return values and which methods change the array in place versus returning a new one.
Know the difference between slice() and splice() without looking it up? Let's find out.
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What This Quiz Covers
- map(), filter(), and reduce() and their return values
- Mutating methods vs. non-mutating methods
- find(), some(), and every() for searching and testing
- slice() for extracting portions of an array
- forEach() and why it always returns undefined
- Chaining array methods together
Sample questions3 of 13 shown
Q1
Which array method returns a new array with elements that pass a test function?
Q2
What does the map() method do?
Q3
What is the return value of forEach()?
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