const flat = arr => [].concat.apply([], arr.map(a => Array.isArray(a) ? flat(a) : a));
// Or
const flat = arr => arr.reduce((a, b) => Array.isArray(b) ? [...a, ...flat(b)] : [...a, b], []);

// Or
// See the browser compatibility at https://caniuse.com/#feat=array-flat
const flat = arr => arr.flat();

// Example
flat(['cat', ['lion', 'tiger']]);   // ['cat', 'lion', 'tiger']

//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)

const ResponsiveCardImg = styled(Card.Img)`
    // For screens wider than 768px
    @media(min-width: 768px) {
        // Your responsive styles here.
    }

    // For screens smaller than 768px
    @media(max-width: 768px) {
        // Your responsive styles here.
    }
`

export default function App() {
    return (
        <MainContainer>
            <Container>
                <Card text='white' bg='dark' style={styles.mainCard}>
                <ResponsiveCardImg
                    style={styles.cardImage}
                    onClick={handleClick}
                    src={apeImage}
                    alt='Degenerate Ape Academy'
                />
                <Card.Body>
                    <Card.Title className='text-center' as='h2'>
                    {apeId}
                    </Card.Title>
                </Card.Body>
                </Card>
            </Container>
        </MainContainer>
    );
}

const compactObject = val => {
  const data = Array.isArray(val) ? val.filter(Boolean) : val;
  return Object.keys(data).reduce(
    (acc, key) => {
      const value = data[key];
      if (Boolean(value))
        acc[key] = typeof value === 'object' ? compactObject(value) : value;
      return acc;
    },
    Array.isArray(val) ? [] : {}
  );
};

const obj = {
  a: null,
  b: false,
  c: true,
  d: 0,
  e: 1,
  f: '',
  g: 'a',
  h: [null, false, '', true, 1, 'a'],
  i: { j: 0, k: false, l: 'a' }
};
compactObject(obj);
// { c: true, e: 1, g: 'a', h: [ true, 1, 'a' ], i: { l: 'a' } }

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

//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}`);