anagram and palindrome algorithms

anagramAndPalindrome.js

// Problem 1 - Palindrome
// Write a function that takes a string as an input
// and returns true if the string is the same string forwards
// and backwards

String.prototype.reverse = function() {
    return this.split("").reverse().join("");
}

const isPalindrome = function(str) {
    if (str.reverse() === str) {
        return true;
    }
    return false;
};

// Problem 2 - Anagram
// Write a function that takes two strings as input and 
// returns true if they contain the exact same characters

/** 
 * @param string str1
 * @param string str2
 * @return boolean
 */

// Solution 1
const isAnagram = function(str1, str2) {
    let sameCharCount;
    let stringContainsChar;

    if (str1.length !== str2.length) {
        return false;
    }

    for (let i=0; i<str1.length; i++) {
        sameCharCount = str2.split(str1[i]).length-1 === str1.split(str1[i]).length-1;
        stringContainsChar = str2.indexOf(str1[i]) !== -1;

        if (stringContainsChar && sameCharCount) {
            return true;
        } else {
            return false;
        }
    }
};

// Solution 2
const isAnagram = function(str1, str2) {
    let sortedStr1 = str1.split("").sort().join("");
    let sortedStr2 = str2.split("").sort().join("");

    if (sortedStr1 === sortedStr2) {
        return true;
    } else {
        return false;
    }
};


// Problem 3 - Another Anagram
// Write a function that takes a single string as input
// and returns a list of all the permutations of that string.

/** 
 * @param string word
 * @return array
 */

// My first solution - solved with my own brain
// but only returns a portion of all the anagrams so 
// its actually broken
var findAllAnagrams = function(word) {
    let result = [];
    for (let i=0; i<=word.length; i++) {
        for (let j=0; j<=word.length; j++) {
            flipped = flipLetters(word, i, j);
            if (result.indexOf(flipped) === -1) {
                result.push(flipped);
            }
        }       
    }
    return result;
};

var flipLetters = function(string, i, j) {
    let tmp = string[i];
    let arr = string.split('');
    arr[i] = arr[j];
    arr[j] = tmp;
    return arr.join('');
};

// Solution 2 - had to get help to solve this
const anagrams = function(word) {
    let result = [];
    if (word.length === 1) {
        result.push(word);
        return result;
    }
    for (let i=0; i<word.length; i++) {
        let currentChar = word[i];
        let remain = word.slice(0, i) + word.slice(i + 1);
        let subResult = anagrams(remain);
        for (let j=0; j<subResult.length;j++) {
            result.push(currentChar + subResult[j]);
        }   
    }
    return result;
};