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permutations

Nov 19, 2022CodeCatch
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Reverse a string in Java

Nov 20, 2022Helper

0 likes • 2 views

new StringBuilder(hi).reverse().toString()

native data structures

Nov 19, 2022CodeCatch

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const nums = [1, 2, 3];
const strs = Array.from('est');
nums.push(6);
nums.push(4, 9);
strs.unshift('t');
nums.length; // 6
nums[nums.length - 1]; // 9
strs[0]; // 't'
strs[2]; // 's'
nums.slice(1, 3); // [2, 3]
nums.map(n => n * 2); // [2, 4, 6, 12, 8, 18]
nums.filter(n => n % 2 === 0); // [2, 6, 4]
nums.reduce((a, n) => a + n, 0); // 25
strs.reverse(); // ['t', 's', 'e', 't']
strs.join(''); // 'test'
const nums = new Set([1, 2, 3]);
nums.add(4);
nums.add(1);
nums.add(5);
nums.add(4);
nums.size; // 5
nums.has(4); // true
nums.delete(4);
nums.has(4); // false
[...nums]; // [1, 2, 3, 5]
nums.clear();
nums.size; // 0
const items = new Map([
[1, { name: 'John' }],
[2, { name: 'Mary' }]
]);
items.set(4, { name: 'Alan' });
items.set(2, { name: 'Jeff' });
items.size; // 3
items.has(4); // true
items.get(2); // { name: 'Jeff' }
items.delete(2);
items.size; // 2
[...items.keys()]; // [1, 4]
[...items.values()]; // [{ name: 'John' }, { name: 'Alan' }]
items.clear();
items.size; // 0

JWT Authentication

Mar 11, 2021C S

0 likes • 1 view

const jwt = require("jsonwebtoken");
const authToken = (req, res, next) => {
const token = req.headers["x-auth-token"];
try {
req.user = jwt.verify(token, process.env.ACCESS_TOKEN_SECRET);
next();
} catch (err) {
console.log(err.message);
res.status(401).json({ msg: "Error authenticating token" });
}
};
module.exports = authToken;

linear search

Nov 19, 2022CodeCatch

0 likes • 3 views

const linearSearch = (arr, item) => {
for (const i in arr) {
if (arr[i] === item) return +i;
}
return -1;
};
linearSearch([2, 9, 9], 9); // 1
linearSearch([2, 9, 9], 7); // -1

Untitled

Apr 14, 2023Helper

0 likes • 8 views

const quickSort = arr => {
const a = [...arr];
if (a.length < 2) return a;
const pivotIndex = Math.floor(arr.length / 2);
const pivot = a[pivotIndex];
const [lo, hi] = a.reduce(
(acc, val, i) => {
if (val < pivot || (val === pivot && i != pivotIndex)) {
acc[0].push(val);
} else if (val > pivot) {
acc[1].push(val);
}
return acc;
},
[[], []]
);
return [...quickSort(lo), pivot, ...quickSort(hi)];
};
console.log(quickSort([1, 6, 1, 5, 3, 2, 1, 4])) // [1, 1, 1, 2, 3, 4, 5, 6]

copyString.js

Nov 8, 2023LeifMessinger

0 likes • 6 views

function copyString(text){
async function navigatorClipboardCopy(text){
if(document.location.protocol != "https:"){
return false;
}
return new Promise((resolve, reject)=>{
navigator.clipboard.writeText(text).then(()=>{resolve(true);}, ()=>{resolve(false);});
});
}
function domCopy(text){
if(!(document.execCommand)){
console.warn("They finally deprecated document.execCommand!");
}
const input = document.createElement('textarea');
input.value = text;
document.body.appendChild(input);
input.select();
const success = document.execCommand('copy');
document.body.removeChild(input);
return success;
}
function promptCopy(){
prompt("Copy failed. Might have ... somewhere. Check console.", text);
console.log(text);
}
function done(){
alert("Copied to clipboard");
}
navigatorClipboardCopy(text).catch(()=>{return false;}).then((success)=>{
if(success){
done();
}else{
if(domCopy(text)){
done();
}else{
promptCopy();
}
}
});
}