Recursion.js

// WRITE RECURSION METHODS

let recursiveSum = (num) => {
    if (num === 1) {
        return 1;
    } else {
        return num + recursiveSum(num-1);
    }
};

console.log(recursiveSum(3));

let recursiveFactorial = (num) => {
    if (num === 1) return 1;
    return num * recursiveFactorial(num-1);
};

console.log(recursiveFactorial(4));

function numOccurencesRecursive(arr, val) {
    if(!arr.length) return 0;
    return (arr[0] === val) + numOccurencesRecursive(arr.slice(1), val);
}

console.log(numOccurencesRecursive("vincevvvv", 'v'));
console.log('word'.slice(1));
console.log('word'.substring(1));

let arr = ['a','b','c','d'];

let reverseArray = (array) => {
    if (!array.length) return array[0];
    return reverseArray(array.slice(1)) + array.slice(0,1);
};

console.log(reverseArray(arr));

let array = [];
array.push("a");
array.push("b");
console.log(array);
console.log(array.pop());
console.log(array);
array.push("d");
array.push("c");
console.log(array);
console.log(array.indexOf('c'));