Esteemed browser and Web standards expert Alex Russell looks at the state of client-side Web performance, what sort of bandwidth you should be taking into account, what devices people are using, and warns against ever-growing JavaScript bundle sizes. A lot of data here.
Alex Russell
Please open Telegram to view this post
VIEW IN TELEGRAM
👍5❤1🤔1
CHALLENGE
class SimpleObservable {
constructor(subscribeFn) {
this.subscribeFn = subscribeFn;
}
subscribe(observer) {
return this.subscribeFn(observer);
}
}
const obs = new SimpleObservable(observer => {
observer.next('first');
observer.next('second');
observer.complete();
});
const results = [];
obs.subscribe({
next: val => results.push(val),
complete: () => results.push('done')
});
console.log(results.join('-'));❤4👍1🤔1
What is the output?
Anonymous Quiz
46%
first-second-done
39%
first-second-complete
10%
first-done-second
4%
done-first-second
Get a Google Calendar-style experience in your own apps. Has connectors for React, Vue and Angular, but can be used with plain JavaScript too. The base version is MIT licensed, but there’s a commercial version too with extra features.
Adam Shaw
Please open Telegram to view this post
VIEW IN TELEGRAM
❤10🤩1
CHALLENGE
const arr = [1, 2, 3];
const obj = { valueOf: () => 4, toString: () => '5' };
const result1 = arr + obj;
const result2 = +obj;
const result3 = String(obj);
const result4 = obj == 4;
const result5 = obj === 4;
console.log(`${result1}|${result2}|${result3}|${result4}|${result5}`);
const weird = [] + [] + 'hello';
const weirder = [] + {} + [];
const weirdest = {} + [] + {};
console.log(`${weird}|${weirder}|${weirdest}`);
const final = !!'0' + !!'' + !!null + !!undefined;
console.log(final);
❤3
Draft diagrams quickly with TypeScript. Define your data models through top-level type aliases and interfaces and it automatically lays out the nodes in an efficient way. GitHub repo.
Andrei Neculaesei
Please open Telegram to view this post
VIEW IN TELEGRAM
❤8👍1
CHALLENGE
const data = '{"users": [{"name": "Sarah", "age": 25}, {"name": "Mike", "age": null}]}';
try {
const parsed = JSON.parse(data);
const result = parsed.users.map(user => {
return user.age ?? 'unknown';
});
console.log(result.join(' - '));
} catch (error) {
console.log('Parse error occurred');
}
const invalidJson = '{"name": "John", age: 30}';
try {
JSON.parse(invalidJson);
console.log('Success');
} catch {
console.log('Invalid');
}❤9
What is the output?
Anonymous Quiz
23%
Parse error occurred, Invalid
38%
25 - null, Success
10%
25 - unknown
30%
25 - unknown, Invalid
👍7🤔2❤1
CHALLENGE
class Logger {
log(msg) {
return `[LOG]: ${msg}`;
}
}
class Formatter {
format(text) {
return text.toUpperCase();
}
}
class Service {
constructor(logger, formatter) {
this.logger = logger;
this.formatter = formatter;
}
process(data) {
const formatted = this.formatter.format(data);
return this.logger.log(formatted);
}
}
const service = new Service(new Logger(), new Formatter());
console.log(service.process('hello world'));What is the output?
Anonymous Quiz
50%
[LOG]: HELLO WORLD
30%
HELLO WORLD
13%
hello world
7%
[LOG]: hello world