Another mammoth Bun release. Bun.Image is a new built-in image processing API which can replace Sharp in many cases. Bun’s package manager has added a global virtual store (akin to pnpm’s), Bun.serve has experimental HTTP/3 over QUIC support, and fetch gets HTTP/2 and HTTP/3 support. Plus the usual raft of Node.js compatibility improvements.
Jarred Sumner
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❤6👍4🤔1
CHALLENGE
const handler = {
get(target, prop, receiver) {
if (prop in target) {
const value = Reflect.get(target, prop, receiver);
return typeof value === "number" ? value * 2 : value;
}
return `Property "${prop}" not found`;
},
set(target, prop, value) {
if (typeof value !== "number") {
throw new TypeError("Only numbers allowed");
}
Reflect.set(target, prop, value ** 2);
return true;
},
has(target, prop) {
return prop.startsWith("_") ? false : prop in target;
},
};
const store = new Proxy({ _secret: 99, score: 5 }, handler);
store.level = 3;
console.log(store.score);
console.log(store.level);
console.log("_secret" in store);
console.log("score" in store);
console.log(store._secret);🔥2
What is the output?
Anonymous Quiz
31%
10 18 false true 198
36%
5 9 false true 198
30%
10 9 false true Property "_secret" not found
3%
10 9 true false 198
CHALLENGE
class Range {
constructor(start, end, step = 1) {
this.start = start;
this.end = end;
this.step = step;
}
[Symbol.iterator]() {
let current = this.start;
const { end, step } = this;
return {
next() {
if (current <= end) {
const value = current;
current += step;
return { value, done: false };
}
return { value: undefined, done: true };
}
};
}
}
const range = new Range(1, 10, 3);
const result = [...range].map(n => n ** 2);
console.log(result);
❤4🔥2
What is the output?
Anonymous Quiz
20%
[ 1, 9, 25, 49 ]
51%
[ 1, 16, 49, 100 ]
17%
[ 1, 9, 49 ]
12%
[ 1, 9, 25, 49, 81 ]
❤4🤔1
CHALLENGE
const p1 = new Promise((resolve) => {
console.log("A");
resolve("B");
});
const p2 = p1.then((val) => {
console.log(val);
return "C";
});
p2.then((val) => console.log(val));
console.log("D");
❤4🤔3
CHALLENGE
class EventEmitter {
#listeners = new Map();
on(event, listener) {
if (!this.#listeners.has(event)) {
this.#listeners.set(event, []);
}
this.#listeners.get(event).push(listener);
return this;
}
emit(event, ...args) {
const handlers = this.#listeners.get(event) ?? [];
handlers.forEach(fn => fn(...args));
return this;
}
}
const emitter = new EventEmitter();
const log = [];
emitter
.on("data", val => log.push(`A:${val}`))
.on("data", val => log.push(`B:${val * 2}`))
.on("end", () => log.push("done"));
emitter.emit("data", 5).emit("data", 3).emit("end");
console.log(log.join(","));
👍2
What is the output?
Anonymous Quiz
36%
A:5,B:10,A:3,B:6,done
34%
A:5,A:3,B:6,B:10,done
26%
A:5,B:10,done,A:3,B:6
4%
A:5,B:25,A:3,B:9,done
❤4
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npm is the only major package manager that runs dependency install scripts (e.g. postinstall) by default, and they’ve become too much of a security weakness, says Jamie, who works for GitHub (maintainers of npm). This RFC features further discussion of the idea and the tradeoffs involved.
Jamie Magee
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CHALLENGE
const createModule = (() => {
const privateCache = new WeakMap();
return function(name) {
const state = { name, version: 1, active: true };
privateCache.set(state, { accessCount: 0 });
return {
getInfo() {
const meta = privateCache.get(state);
meta.accessCount++;
return `${state.name}@v${state.version}`;
},
getAccessCount() {
return privateCache.get(state).accessCount;
},
upgrade() {
state.version++;
return this;
}
};
};
})();
const mod = createModule("auth");
mod.upgrade().upgrade();
console.log(mod.getInfo());
console.log(mod.getAccessCount());
❤2👍2
Mark, well known for maintaining Redux and creating Redux Toolkit, goes deep into his daily development workflow, including his use of OpenCode (an open source JavaScript-powered coding agent), how he manages his knowledge base, tasks, and more.
Mark Erikson
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❤6👍2🔥1
CHALLENGE
const str = "JavaScript is Awesome!";
const result = str
.split(" ")
.map((word, i) =>
i % 2 === 0
? word.toUpperCase()
: word.toLowerCase()
)
.join("-");
const reversed = result
.split("")
.reduce((acc, char) => char + acc, "");
console.log(reversed);
What is the output?
Anonymous Quiz
40%
!EMOSEWA-si-TPIRCSAVAJ
23%
!emosewa-is-tpircsavaj
23%
!EMOSEWA-IS-TPIRCSAVAJ
15%
!emosewa-IS-tpircsavaj
❤2🔥1
Given a valid OpenAPI v3 or Swagger v2 spec, generate models, requests, hooks, and mocks for React, Vue, Svelte, Solid, and Hono apps, or even plain fetch.
Victor Bury
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CHALLENGE
const delay = (ms, val) => new Promise(res => setTimeout(res, ms, val));
async function* asyncGen() {
yield await delay(10, "alpha");
yield await delay(10, "beta");
yield await delay(10, "gamma");
}
async function run() {
const results = [];
const gen = asyncGen();
const [first, , third] = await Promise.all([
gen.next(),
gen.next(),
gen.next()
]);
results.push(first.value, third.value);
const p1 = Promise.resolve("x").then(v => v + "1");
const p2 = Promise.reject("err").catch(e => e + "2");
results.push(...(await Promise.all([p1, p2])));
console.log(results);
}
run();
❤3👍1
What is the output?
Anonymous Quiz
17%
[ 'alpha', 'gamma', 'x1', 'err' ]
31%
[ 'alpha', 'beta', 'x1', 'err2' ]
19%
[ 'alpha', 'beta', 'x1', 'err' ]
33%
[ 'alpha', 'gamma', 'x1', 'err2' ]
❤1