Hello, checkiomates🐱👤!
We trace the fascinating history of the language, explore the convenience of the new Array.prototype.at() method for easier array indexing, and challenge your understanding of JavaScript's unique behaviors with a "guess the output" quiz. To top it off, we present a mission to count intersecting pairs of disks on a two-dimensional plane, putting your geometric and algorithmic skills to the test.
💡TIP
At every mission page, under the editor window, there is a terminal window. If you want to discover all CheckiO features, visit our tutorial. It's a longread, but it's worth it!
🏁MISSION
Overlapping Disks by freeman_lex -
Given an array of disks on the two-dimensional plane represented as tuples [x, y, r] so that x, y is the center point and r is the radius of that disk, count how many pairs of disks intersect.
assert.strictEqual(
overlappingDisks([
[0, 0, 3],
[6, 0, 3],
[6, 6, 3],
[0, 6, 3],
]),
4
);
assert.strictEqual(
overlappingDisks([
[4, -1, 3],
[-3, 3, 2],
[-3, 4, 2],
[3, 1, 4],
]),
2
);
📖ARTICLES
A Brief History of JavaScript -
JavaScript (originally named LiveScript) turns thirty years old this year and the Deno team has put together a fantastic timeline-based tour of how much things have progressed from its first appearance in Netscape Navigator, through offshoots like JScript, standardization, and the introduction of Node.js, all the way through to the modern day.
How at() method makes array indexing easier -
Working with arrays in JavaScript is an everyday thing for front-end developers. We reach for arrays constantly — whether we’re rendering lists, managing state, or juggling DOM elements. But what if I told you there’s a more elegant way to access elements at a specific index — especially the last one? Now we can…with Array.prototype.at().
Guess the Output is a fun multi-choice JavaScript quiz to put your knowledge to the test. Each answer is explained as you go.
👩💻CODE SHOT
What do you think the following code does?
function ????????(text: string): string {
return text.split("").reverse().join("").split(" ").reverse().join(" ")
}
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