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linked list

0 likes • Nov 19, 2022
JavaScript
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Get timezone as a string

CodeCatch
0 likes • Nov 19, 2022
JavaScript
const getTimezone = () => Intl.DateTimeFormat().resolvedOptions().timeZone;
// Example
getTimezone();

doubly linked list

CodeCatch
0 likes • Nov 19, 2022
JavaScript
class DoublyLinkedList {
constructor() {
this.nodes = [];
}
get size() {
return this.nodes.length;
}
get head() {
return this.size ? this.nodes[0] : null;
}
get tail() {
return this.size ? this.nodes[this.size - 1] : null;
}
insertAt(index, value) {
const previousNode = this.nodes[index - 1] || null;
const nextNode = this.nodes[index] || null;
const node = { value, next: nextNode, previous: previousNode };
if (previousNode) previousNode.next = node;
if (nextNode) nextNode.previous = node;
this.nodes.splice(index, 0, node);
}
insertFirst(value) {
this.insertAt(0, value);
}
insertLast(value) {
this.insertAt(this.size, value);
}
getAt(index) {
return this.nodes[index];
}
removeAt(index) {
const previousNode = this.nodes[index - 1] || null;
const nextNode = this.nodes[index + 1] || null;
if (previousNode) previousNode.next = nextNode;
if (nextNode) nextNode.previous = previousNode;
return this.nodes.splice(index, 1);
}
clear() {
this.nodes = [];
}
reverse() {
this.nodes = this.nodes.reduce((acc, { value }) => {
const nextNode = acc[0] || null;
const node = { value, next: nextNode, previous: null };
if (nextNode) nextNode.previous = node;
return [node, ...acc];
}, []);
}
*[Symbol.iterator]() {
yield* this.nodes;
}
}
const list = new DoublyLinkedList();
list.insertFirst(1);
list.insertFirst(2);
list.insertFirst(3);
list.insertLast(4);
list.insertAt(3, 5);
list.size; // 5
list.head.value; // 3
list.head.next.value; // 2
list.tail.value; // 4
list.tail.previous.value; // 5
[...list.map(e => e.value)]; // [3, 2, 1, 5, 4]
list.removeAt(1); // 2
list.getAt(1).value; // 1
list.head.next.value; // 1
[...list.map(e => e.value)]; // [3, 1, 5, 4]
list.reverse();
[...list.map(e => e.value)]; // [4, 5, 1, 3]
list.clear();
list.size; // 0

Date Time Testing

AustinLeath
0 likes • Nov 18, 2022
JavaScript
var d = new Date();
var d = new Date(milliseconds);
var d = new Date(dateString);
var d = new Date(year, month, day, hours, minutes, seconds, milliseconds);
// Vanilla JS Solution:
var app = document.getElementById('app');
var typewriter = new Typewriter(app, { loop: true });
typewriter
.typeString("I'm John and I'm a super cool web developer")
.pauseFor(3000)
.deleteChars(13) // "web developer" = 13 characters
.typeString("person to talk with!") // Will display "I'm John and I'm a super cool person to talk with!"
.start();
// React Solution:
import Typewriter from 'typewriter-effect';
<Typewriter
options={{ loop: true }}
onInit={typewriter => {
typewriter
.typeString("I'm John and I'm a super cool web developer")
.pauseFor(3000)
.deleteChars(13) // "web developer" = 13 characters
.typeString("person to talk with!") // Will display "I'm John and I'm a super cool person to talk with!"
.start();
}}
/>

unzipWith() function

CodeCatch
0 likes • Nov 19, 2022
JavaScript
const unzipWith = (arr, fn) =>
arr
.reduce(
(acc, val) => (val.forEach((v, i) => acc[i].push(v)), acc),
Array.from({
length: Math.max(...arr.map(x => x.length))
}).map(x => [])
)
.map(val => fn(...val));
unzipWith(
[
[1, 10, 100],
[2, 20, 200],
],
(...args) => args.reduce((acc, v) => acc + v, 0)
);
// [3, 30, 300]

Subsets of an array

CodeCatch
0 likes • Nov 19, 2022
JavaScript
const getSubsets = arr => arr.reduce((prev, curr) => prev.concat(prev.map(k => k.concat(curr))), [[]]);
// Examples
getSubsets([1, 2]); // [[], [1], [2], [1, 2]]
getSubsets([1, 2, 3]); // [[], [1], [2], [1, 2], [3], [1, 3], [2, 3], [1, 2, 3]]