What is the output?
Anonymous Quiz
45%
Rex makes a sound and barks true Dog
22%
Rex barks false Dog
24%
Rex makes a sound and barks true Animal
9%
Rex makes a sound true Dog
👍9🤔1
Each year, Devographics runs an epic survey of as many JavaScript community members as it can and turns the results into an interesting report on the state of the ecosystem – here’s the results from 2024. If you have the time, fill it in, especially as they format it in a way where you can actually learn about stuff as you go.
Devographics
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❤2🤔2🔥1
CHALLENGE
class DataProcessor {
constructor(value) {
this.value = value;
}
transform(fn) {
return new DataProcessor(fn(this.value));
}
getValue() {
return this.value;
}
}
const multiply = x => x * 2;
const add = x => x + 10;
const square = x => x * x;
const result = new DataProcessor(5)
.transform(multiply)
.transform(add)
.transform(square)
.getValue();
console.log(result);❤1
❤8👍3🔥1
CHALLENGE
const Flyable = {
fly() { return 'flying'; }
};
const Swimmable = {
swim() { return 'swimming'; }
};
function mixin(Base, ...mixins) {
mixins.forEach(mixin => Object.assign(Base.prototype, mixin));
return Base;
}
class Bird {}
class Fish {}
const FlyingFish = mixin(class extends Fish {}, Flyable, Swimmable);
const instance = new FlyingFish();
console.log(instance.swim());
console.log(instance.fly());
console.log(instance instanceof Fish);What is the output?
Anonymous Quiz
20%
flying, swimming, false
48%
swimming, flying, true
23%
undefined, undefined, true
8%
swimming, flying, false
❤1🤔1
CHALLENGE
function createCounter() {
let count = 0;
return function(increment = 1) {
count += increment;
return count;
};
}
const counter1 = createCounter();
const counter2 = createCounter();
console.log(counter1());
console.log(counter1(5));
console.log(counter2(3));
console.log(counter1());
console.log(counter2());❤10🤔5
CHALLENGE
const arr = [1, 2, 3, 4, 5];
const obj = { a: 1, b: 2, c: 3 };
const result1 = Object.keys(obj).length;
const result2 = arr.length;
delete obj.b;
obj.d = 4;
const result3 = Object.keys(obj).length;
const result4 = arr.push(6);
arr.length = 3;
const result5 = arr.length;
const result6 = Object.keys(obj).join('');
console.log(result1, result2, result3, result4, result5, result6);
🤔2
What is the output?
Anonymous Quiz
16%
2 5 3 6 3 acd
31%
3 5 2 6 3 adc
17%
3 5 3 7 3 acd
36%
3 5 3 6 3 acd
❤6👍1🔥1
The maintainers of the Deno runtime reflect on the recent npm ecosystem security issues and show off how Deno’s non-permissive explicit ‘secure by default’ model can help.
Andy Jiang
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❤5🔥3👍2🤩1
CHALLENGE
const multiply = (a) => (b) => (c) => a * b * c;
const step1 = multiply(2);
const step2 = step1(3);
const result1 = step2(4);
const partialMult = multiply(5)(6);
const result2 = partialMult(7);
const directResult = multiply(1)(8)(9);
console.log(result1);
console.log(result2);
console.log(directResult);
console.log(typeof step1);
console.log(typeof partialMult);
❤1
What is the output?
Anonymous Quiz
25%
24 210 72 object object
22%
6 18 9 function function
24%
NaN NaN NaN function function
29%
24 210 72 function function
🤣5👍3❤1
Many features that once required third-party packages are now built into the runtime itself. Here’s a look at some of the most notable that you may want to experiment with, prior to reducing unnecessary dependencies.
Lizz Parody
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❤8🔥3
CHALLENGE
function mystery(arr, depth = 0) {
if (arr.length <= 1) return arr;
const mid = Math.floor(arr.length / 2);
const left = mystery(arr.slice(0, mid), depth + 1);
const right = mystery(arr.slice(mid), depth + 1);
const result = [];
let i = 0, j = 0;
while (i < left.length && j < right.length) {
result.push(left[i] <= right[j] ? left[i++] : right[j++]);
}
return result.concat(left.slice(i)).concat(right.slice(j));
}
const arr = [3, 1, 4, 1, 5];
console.log(mystery(arr));❤4
What is the output?
Anonymous Quiz
24%
[5, 4, 3, 1, 1]
43%
[1, 1, 3, 4, 5]
17%
[1, 3, 1, 4, 5]
17%
[3, 1, 4, 1, 5]
🔥3❤2👍1
We're thrilled that React is coming under the The Linux Foundation to create the React Foundation.
React doesn’t live in isolation - It works alongside Node.js, Electron, Webpack, and more. A dedicated foundation means more collaboration, security, and sustainability across the ecosystem.
OpenJS Foundation
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❤8👍7🤔1
CHALLENGE
const ws = new WeakSet();
const obj1 = { name: 'first' };
const obj2 = { name: 'second' };
const obj3 = obj1;
ws.add(obj1);
ws.add(obj2);
ws.add(obj3);
console.log(ws.has(obj1));
console.log(ws.has(obj3));
console.log(ws.has({ name: 'first' }));
console.log(ws.size);
❤2
What is the output?
Anonymous Quiz
12%
true false false undefined
41%
true true false 3
26%
true true true undefined
21%
true true false undefined
❤3👍3🔥1
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CHALLENGE
const obj = {
name: 'Sarah',
greet: () => {
console.log(`Hello, ${this.name}`);
},
sayHi: function() {
const inner = () => {
console.log(`Hi, ${this.name}`);
};
inner();
}
};
obj.greet();
obj.sayHi();