[Discussion] Ideas for new Concepts

[junedev]

Concept Roadmap

There are already a lot of ideas for additional concepts that we could cover with concept exercises in the future.
You can find a list in our roadmap document: Roadmap - Potential Future Concepts

We already created issues for the following new concepts/exercises:

• Implement new Concept Exercise: Template Strings and Ternary #1009
• Implement new Concept Exercise: Classes #1015 (claimed)
• Implement new Concept Exercise: Async/Await #1502 (claimed)
• Implement new Concept Exercise: Regular Expressions #1506
• Implement new Concept Exercise: Randomness #1515 (claimed)
• Implement new Concept Exercise: Dates #1528 (claimed)
• Separate rest-and-spread into its own new concept exercise (concept exists) #1500
• Elyses Destructered Enchantments: Add object destructering and remove rest and spread #1501

Additionally some concept exercises that exist but need major improvements are not yet visible on the website (status "wip"), see #1415.

Purpose of this issue

• Suggest additional concepts to cover that are not on the roadmap yet.
• Comment on which concept from the roadmap you would like to see implemented first.
• Volunteer for creating a certain concept exercise that does not have an issue yet, so a maintainer can write up an issue with some basic guidelines for you.
• General discussion about how to divide concepts/ how to structure the concept tree.
• etc

[junedev]

Additional ideas by @Steffan153 (posted here #951 (comment), items already on the roadmap are omitted below):

• WeakMap/WeakSet
• WeakRef and FinalizationRegistry
• Proxy and Reflect (reflect is not on the list yet)
• Decorators

[scottmcook]

I'd like to suggest adding a functional composition concept. The exercise coordinate-transformation mentions them but the exercise only covers the concept of closures.

[Codeboy20]

I’d like to suggest adding a new concept covering Symbols and Well-Known Symbols.

Why:
– Symbols are a fundamental but often underexplored part of JavaScript.
– They allow creation of unique property keys and are central to meta-programming.
– Introducing Well-Known Symbols (like Symbol.iterator, Symbol.toStringTag, etc.) would help learners understand iteration protocols and object customization.

This concept would bridge the gap between basic object handling and more advanced topics like proxies or custom iteration.

[SleeplessByte]

@Codeboy20 I'd love this. I have actually been using (well-known) Symbol in several exercises to limit how people can solve them.

for ...of iteration (and logging):

javascript/exercises/concept/train-driver/train-driver.spec.js

Lines 15 to 47 in 17c0f6f

	class LimitedArray {
	constructor(values) {
	this.values = values;
	}
	// Enables rest syntax and spread operator, as wel as for of, etc.
	[Symbol.iterator]() {
	return this.values[Symbol.iterator]();
	}
	// Log value in non-upgraded environments
	toString() {
	return this.values.toString();
	}
	// Overrides logging in node (ie. students working locally)
	[customInspectSymbol](depth, inspectOptions, inspect) {
	const inner = this.values[customInspectSymbol]
	? this.values[customInspectSymbol](depth, inspectOptions, inspect)
	: this.values.toString();
	return `List of (${inner})`;
	}
	// Overrides log overrides in web environment (ie. students working in editor)
	[customLogSymbol](depth, inspectOptions, inspect) {
	const inner = this.values[customLogSymbol]
	? this.values[customLogSymbol](depth, inspectOptions, inspect)
	: this.values.toString();
	return `List of (${inner})`;
	}
	}

Branded check for instanceof

javascript/exercises/concept/recycling-robot/lib.js

Lines 1 to 18 in 17c0f6f

	const certification = Symbol('Certification');
	export class ElectronicDevice {
	// This class will be used in the exercise.
	static [Symbol.hasInstance](instance) {
	return instance && instance.__certification === certification;
	}
	constructor() {
	Object.defineProperty(this, '__certification', {
	enumerable: false,
	writable: false,
	configurable: false,
	value: certification,
	});
	}
	}

I definitely think we could use that exercise to open a path towards metaprogramming.

Is this something you'd like to work on?

[Codeboy20]

@Codeboy20 I'd love this. I have actually been using (well-known) Symbol in several exercises to limit how people can solve them.

for ...of iteration (and logging):

javascript/exercises/concept/train-driver/train-driver.spec.js

Lines 15 to 47 in 17c0f6f

class LimitedArray {
constructor(values) {
this.values = values;
}

// Enables rest syntax and spread operator, as wel as for of, etc.
Symbol.iterator {
return this.valuesSymbol.iterator;
}

// Log value in non-upgraded environments
toString() {
return this.values.toString();
}

// Overrides logging in node (ie. students working locally)
[customInspectSymbol](depth, inspectOptions, inspect) {
const inner = this.values[customInspectSymbol]
? this.values[customInspectSymbol](depth, inspectOptions, inspect)
: this.values.toString();

 return `List of (${inner})`; 

}

// Overrides log overrides in web environment (ie. students working in editor)
[customLogSymbol](depth, inspectOptions, inspect) {
const inner = this.values[customLogSymbol]
? this.values[customLogSymbol](depth, inspectOptions, inspect)
: this.values.toString();

 return `List of (${inner})`; 

}
}

Branded check for instanceof

javascript/exercises/concept/recycling-robot/lib.js

Lines 1 to 18 in 17c0f6f

const certification = Symbol('Certification');

export class ElectronicDevice {
// This class will be used in the exercise.

static Symbol.hasInstance {
return instance && instance.__certification === certification;
}

constructor() {
Object.defineProperty(this, '__certification', {
enumerable: false,
writable: false,
configurable: false,
value: certification,
});
}
}
I definitely think we could use that exercise to open a path towards metaprogramming.

Is this something you'd like to work on?

yes , definitely

[SleeplessByte]

Go for it. Do you know where to start?