Data Structures

How you store and manipulate data.

Maps
Completion percentage: 92.4% (21954)
Completion percentage: 92.4% (21954)

Percents
Count
The Map object holds key-value pairs and remembers the original insertion order of the keys.

2019

2020

Have used it
Know about it
Never heard of it

Sets
Completion percentage: 92.6% (22010)
Completion percentage: 92.6% (22010)

Percents
Count
The Set object lets you store unique values of any type, whether primitive values or object references.

2019

2020

Have used it
Know about it
Never heard of it
We asked members of the JavaScript community to share their “pick of the year”

My 2020 Pick: Josh W. Comeau

Josh Comeau has been an inspiration to me, and I can say the JS community in general. He writes very thoughtful articles on his blog, and they are some of the best I read in 2020 because they either helped me stay on top of the latest in JavaScript or helped me learn something new.

We asked members of the JavaScript community to share their “pick of the year”

Gift Egwuenu

Frontend Developer @ PassionatePeople

Typed Arrays
Completion percentage: 92.7% (22032)
Completion percentage: 92.7% (22032)

Percents
Count
JavaScript typed arrays are array-like objects that provide a mechanism for reading and writing raw binary data in memory buffers.

2019

2020

Have used it
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Never heard of it
Percents
Count
The flat() method creates a new array with all sub-array elements concatenated into it recursively up to the specified depth.

2019

2020

Have used it
Know about it
Never heard of it

BigInt
Completion percentage: 93.4% (22186)
Completion percentage: 93.4% (22186)

Percents
Count
BigInt is a built-in object that provides a way to represent whole numbers larger than 253 - 1, which is the largest number JavaScript can reliably represent with the Number primitive and represented by the Number.MAX_SAFE_INTEGER constant. BigInt can be used for arbitrarily large integers.

2020

Have used it
Know about it
Never heard of it

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