forEach Exercise created by jsmayo - https://repl.it/@jsmayo/forEach-Exercise

forEach Exercise.js

/*
Write a function called doubleValues which accepts an array and returns a new array with all the values in the array passed to the function doubled

Examples:
    doubleValues([1,2,3]) // [2,4,6]
    doubleValues([5,1,2,3,10]) // [10,2,4,6,20]

*/
function doubleValues(arr){
    const newArr = [];
    arr.forEach((val) => {
        newArr.push(val * 2);
    });
    return newArr;
}
console.log(doubleValues([1,2,3,4]));
/*
Write a function called onlyEvenValues which accepts an array and returns a new array with only the even values in the array passed to the function

Examples:
    onlyEvenValues([1,2,3]) // [2]
    onlyEvenValues([5,1,2,3,10]) // [2,10]

*/
function onlyEvenValues(arr){
  const arr2 = [];
    arr.forEach((val) => {
      if(val % 2 === 0) arr2.push(val);
    });
    return arr2;
}
console.log(onlyEvenValues([1,2,3,4]));

/*
Write a function called showFirstAndLast which accepts an array of strings and returns a new array with only the first and last character of each string.

Examples:
    showFirstAndLast(['colt','matt', 'tim', 'udemy']) // ["ct", "mt", "tm", "uy"]
    showFirstAndLast(['hi', 'goodbye', 'smile']) // ['hi', 'ge', 'se']

*/
function showFirstAndLast(arr){
    const arr2 = [];
    arr.forEach(function(val) {
        arr2.push(val[0] + val[val.length-1]);
    });
    return arr2;
}
console.log(showFirstAndLast(['colt','matt', 'tim', 'udemy']));


/*
Write a function called addKeyAndValue which accepts an array of objects, a key, and a value and returns the array passed to the function with the new key and value added for each object 

Examples:
    addKeyAndValue([{name: 'Elie'}, {name: 'Tim'}, {name: 'Matt'}, {name: 'Colt'}], 'title', 'instructor') 
    
    // [{name: 'Elie', title:'instructor'}, {name: 'Tim', title:'instructor'}, {name: 'Matt', title:'instructor'}, {name: 'Colt', title:'instructor'}]

*/
function addKeyAndValue(arr,key,value){
    //const arr2 = [];
    arr.forEach(function(val) {
/* 
NOTES:
  * Remember that if you try to add a new key to an object that it will append
    that key to the object automatically.
  * Remember that you cannot use dot notation to add a new unless using quotes,
    since dot notation is literal intrepreted. 
      i.e       val.key = value will add key: 'instructor' 
          BUT   val[key] adds title: 'instructor'
          B/C   the key value can be intrepreted as an argument. 
*/
      val[key] = value;
    });
    return arr;
}
console.log(addKeyAndValue([{name: 'Elie'}, {name: 'Tim'}, {name: 'Matt'}, {name: 'Colt'}], 'title', 'instructor'));

/*
Write a function called vowelCount which accepts a string and returns an object with the keys as the vowel and the values as the number of times the vowel appears in the string. This function should be case insensitive so a lowercase letter and uppercase letter should count

Examples:
    vowelCount('Elie') // {e:2,i:1};
    vowelCount('Tim') // {i:1};
    vowelCount('Matt') // {a:1})
    vowelCount('hmmm') // {};
    vowelCount('I Am awesome and so are you') // {i: 1, a: 4, e: 3, o: 3, u: 1};
*/
function vowelCount(str){
    var splitArr = str.toLowerCase().split("");
    var obj = {};
    var vowels = "aeiou";

    splitArr.forEach(function(letter){
        if(vowels.indexOf(letter) !== -1){
            if(obj[letter]){
                obj[letter]++;
            } else{
                obj[letter] = 1;
            }
        }
    });
    return obj;
}
console.log( vowelCount('Elie'));