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Feb 5, 2021LeifMessinger
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More JavaScript Posts

Check if array is empty

Nov 19, 2022CodeCatch

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arr = [] // empty array
const isEmpty = arr => !Array.isArray(arr) || arr.length === 0;
// Examples
isEmpty([]); // true
isEmpty([1, 2, 3]); // false

Get timezone as a string

Nov 19, 2022CodeCatch

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const getTimezone = () => Intl.DateTimeFormat().resolvedOptions().timeZone;
// Example
getTimezone();

Destructuring Assignment

Nov 19, 2022CodeCatch

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//JavaScript program to swap two variables
//take input from the users
let a = prompt('Enter the first variable: ');
let b = prompt('Enter the second variable: ');
//using destructuring assignment
[a, b] = [b, a];
console.log(`The value of a after swapping: ${a}`);
console.log(`The value of b after swapping: ${b}`);

stripe api json iteration

Nov 18, 2022AustinLeath

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var arr = [{
"success": true,
"data": [
{
"id": "ipi_1KrrbvDOiB2klwsKhuqUWqt1",
"object": "issuing.transaction",
"amount": -2743,
"amount_details": {
"atm_fee": null
},
"authorization": "iauth_1KrrbuDOiB2klwsKoFjQZhhd",
"balance_transaction": "txn_1KrrbwDOiB2klwsK1YkjJJRi",
"card": "ic_1Krqe5DOiB2klwsK44a35eiE",
"cardholder": "ich_1KrqL8DOiB2klwsKtBnZhzYr",
"created": 1650753567,
"currency": "usd",
"dispute": null,
"livemode": false,
"merchant_amount": -2743,
"merchant_currency": "usd",
"merchant_data": {
"category": "advertising_services",
"category_code": "7311",
"city": "San Francisco",
"country": "US",
"name": "Aeros Marketing, LLC",
"network_id": "1234567890",
"postal_code": "94103",
"state": "CA"
},
"metadata": {},
"type": "capture",
"wallet": null
},
{
"id": "ipi_1Krrbvc62B2klwsKhuqUWqt1",
"object": "issuing.transaction",
"amount": -9999,
"amount_details": {
"atm_fee": null
},
"authorization": "iauth_1KrrbuDOiB2klwsKoFjQZhhd",
"balance_transaction": "txn_1KrrbwDOiB2klwsK1YkjJJRi",
"card": "ic_1Krqe5DOiB2klwsK44a35eiE",
"cardholder": "ich_1KrqL8DOiB2klwsKtBnZhzYr",
"created": 1650753567,
"currency": "USD",
"dispute": null,
"livemode": false,
"merchant_amount": -9999,
"merchant_currency": "usd",
"merchant_data": {
"category": "fast_food",
"category_code": "7311",
"city": "San Francisco",
"country": "US",
"name": "Aeros Marketing, LLC",
"network_id": "1234567890",
"postal_code": "94103",
"state": "CA"
},
"metadata": {},
"type": "capture",
"wallet": null
}
]
}];
const reduced = arr.reduce((prev, curr) => {
prev.push({
amount: curr.data[0].merchant_amount,
id: curr.data[0].id,
currency: curr.data[0].currency,
category: curr.data[0].merchant_data.category
});
console.log(prev)
return prev;
}, []);

Mongoose Model

Mar 11, 2021C S

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const mongoose = require('mongoose')
const UserSchema = new mongoose.Schema({
username: {
type: String,
required: true
},
email: {
type: String,
unique: true,
required: true
},
password: {
type: String,
required: true
},
date: {
type: Date,
default: Date.now
}
})
module.exports = User = mongoose.model('user', UserSchema)

linked list

Nov 19, 2022CodeCatch

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class LinkedList {
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 };
if (previousNode) previousNode.next = 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];
const nextNode = this.nodes[index + 1] || null;
if (previousNode) previousNode.next = nextNode;
return this.nodes.splice(index, 1);
}
clear() {
this.nodes = [];
}
reverse() {
this.nodes = this.nodes.reduce(
(acc, { value }) => [{ value, next: acc[0] || null }, ...acc],
[]
);
}
*[Symbol.iterator]() {
yield* this.nodes;
}
}
const list = new LinkedList();
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.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