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graph example

Nov 19, 2022CodeCatch
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More JavaScript Posts

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]

Invert Binary Tree

Oct 15, 2022CodeCatch

2 likes • 8 views

var invertTree = function(root) {
const reverseNode = node => {
if (node == null) {
return null
}
reverseNode(node.left);
reverseNode(node.right);
let holdLeft = node.left;
node.left = node.right;
node.right = holdLeft;
return node;
}
return reverseNode(root);
};

Untitled

Feb 21, 2025leafboo

0 likes • 2 views

console.log("hello world")

Subsets of an array

Nov 19, 2022CodeCatch

0 likes • 2 views

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]]

retryPromise.js

Oct 20, 2023LeifMessinger

0 likes • 20 views

//Retries maxRetries number of times, meaning that if you have 0, then it'll run the function once.
async function retryPromise(promiseFn, maxRetries = 3, delayOffset = 0, delayRandomRange = 0) {
return new Promise((resolve, reject) => {
promiseFn()
.then(resolve, (error) => { //On error
if (maxRetries <= 0) {
return reject(error);
} else {
if(delayRandomRange * Math.random() + delayOffset < 1.0){
return retryPromise(promiseFn, maxRetries - 1, delayOffset, delayRandomRange).then(resolve, reject);
}else{
return new Promise((resolveTwo, rejectTwo) => {
setTimeout(() => {
return retryPromise(promiseFn, maxRetries - 1, delayOffset, delayRandomRange).then(resolveTwo, rejectTwo);
}, delayRandomRange * Math.random() + delayOffset);
}).then(resolve, reject);
}
}
});
});
}
//Tests for that function.
//Returns a function that will fail numTimes times, then will return aValue
function functionThatReturnsAFunctionThatFailsACoupleTimes(numTimes, aValue){
return async function(){
if(numTimes == 0){
return aValue;
}
numTimes--;
throw false;
};
}
const SMALL_NUMBER = 10;
function testTest(failNumberOfTimes){
let functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(failNumberOfTimes, true);
//Test my test
for(let i = 0; i < (failNumberOfTimes * 2); ++i){
function evalTest(val){
let testTestFailedReason = "";
if(val === undefined){
testTestFailedReason = "Test test returned undefined for some reason.";
}
if((i + 1) > failNumberOfTimes){
if(val === true){
//We're good
}else{
testTestFailedReason = "Test test didn't return true when it should have.";
}
}else{
if(val === false){
//We're good
}else{
testTestFailedReason = "Test test didn't return false when it should have.";
}
}
testTestFailedReason = testTestFailedReason || "Test test passed test case";
console.log(testTestFailedReason, "at index", i, "where the function returned", val);
}
functionThatFailsACoupleTimes().then(evalTest, evalTest)
};
}
testTest(SMALL_NUMBER);
let testCaseCounter = 1;
const throwsNoError = [
(val)=>{
if(val == true){
console.log("Passed test case " + (testCaseCounter++));
}else{
console.error("Unexpected return value", val);
}
},
()=>{
console.error("It wasn't supposed to fail!")
}
]
const throwsError = [
(val)=>{
console.error("It wasn't supposed to succeed!", val);
},
(val)=>{
if(val == false){
console.log("Passed test case " + (testCaseCounter++));
}else{
console.error("Unexpected return value", val);
}
}
];
//Runs SMALL_NUMBER times, because SMALL_NUMBER - 1 is the number of retries after the first one
let functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(SMALL_NUMBER - 1, true);
retryPromise(functionThatFailsACoupleTimes, SMALL_NUMBER - 1).then(...throwsNoError)
functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(SMALL_NUMBER - 1, true);
//Runs SMALL_NUMBER - 1 times, because SMALL_NUMBER - 2 is the number of retries after the first one
retryPromise(functionThatFailsACoupleTimes, SMALL_NUMBER - 2).then(...throwsError)
//Testing the delay. You'll have to wait a bit too.
functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(SMALL_NUMBER - 1, true);
//Runs SMALL_NUMBER times, because SMALL_NUMBER - 1 is the number of retries after the first one
retryPromise(functionThatFailsACoupleTimes, SMALL_NUMBER - 1, 500, 500).then(...throwsNoError)
functionThatFailsACoupleTimes = functionThatReturnsAFunctionThatFailsACoupleTimes(SMALL_NUMBER - 1, true);
//Runs SMALL_NUMBER - 1 times, because SMALL_NUMBER - 2 is the number of retries after the first one
retryPromise(functionThatFailsACoupleTimes, SMALL_NUMBER - 2, 500, 500).then(...throwsError)

Redux Setup

Mar 11, 2021C S

0 likes • 2 views

import { configureStore } from "@reduxjs/toolkit";
import { combineReducers } from "redux";
import profile from "./profile";
import auth from "./auth";
import alert from "./alert";
const reducer = combineReducers({
profile,
auth,
alert,
});
const store = configureStore({ reducer });
export default store;