array-functions.js

//Your boss has told you to build a function called map. Follow these instructions to do so.
//https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map
//on the first line, create a new empty array and store in a variable named whatever you want (myNewArray)
//loop theArray and extract the single item from the array per loop and store it in a variable
//on each loop call fnc() passing in the item from the current loop into the call to fnc
//fnc is a function that must return something, capture whatever it returns in a variable
//add the returned value from fnc to the new array
//after looping, return the new array
export function map(theArray, fnc){
    arr = [];

    theArray.forEach(el => {
        arr.push(fnc(el));
    });

    return arr;
}

//create a new array
//loop theArray and call the fnc for each thing in the array, 
//     passing in the item from the current loop
//fnc will return true or false, if true add the item to the new array else do not
//return the new array
export function filter(theArray, fnc){
    arr = [];

    theArray.forEach(el => {
        if (fnc(el)) {
          arr.push(fnc(el));
        }
    });

    return arr;
}


//loop theArray and call the fnc for each thing in the array, 
//     passing in the item from the current loop
//fnc will return true or false, if true return the item 
//return null
export function find(theArray, fnc){
    arr = [];

    theArray.forEach(el => {
        if (fnc(el)) {
          arr.push(fnc(el));
}
    });

    return arr[0];
}


//return the last item in theArray
export function findLast(theArray){
    return theArray[theArray.length - 1];
}

//return the first element of the array
export function head(theArray){
    return theArray[0];
}

//create a new array
//loop theArray in reverse order
//add the item from each loop to the new array
//return the new array
export function reverse(theArray){
    arr = [];

    theArray.forEach(el => {
        arr.unshift(el);
    });

    return arr;
}

//create a new array
//loop theArray
//add the item from each loop to the new array except the first item
//return the new array
export function tail(theArray){
    arr = [];

    theArray.forEach(el => {
        arr.push(el);
    });
  
    arr.shift();
    return arr;
}

// TOO COMPLICATED!:
//implement the most basic sorting algorithm there is
//assume the array will always have numbers
//use a while loop to constantly loop theArray until it is sorted
//use a for loop to loop theArray
//look at the current item and the next item, compare them
//if the items are out of order, swap them
//initialize a variable that indicates if a swap had to be done, set it to false
//if a swap is done set it to true
//after each for loop check the variable, if true, continue the while loop
//if false return theArray
export function sort(theArray){
    sortedArr = [];

    theArray.forEach( (el, i, arr) => {
        if (i == 0) {
            sortedArr.push(el);
        } else if (el >= arr[i - 1]) {
            sortedArr.push(el);
        } else {
            sortedArr.unshift(el);
        }
    });

    return sortedArr;
}