arraryMAP.js

//this is how .map works!!!


Array.prototype.mapOver = function(callback) {
    var newArray = [] // since we're returning an array, we'll start with an empty vessel for the contents of that array.
    for (var i = 0; i < this.length; i ++) { // we're iterating over *the array that is calling* the method.
        newArray.push(callback(this[i])) // we invoke the callback with an array element as input, and we push the return value onto our new array.
    }
    return newArray // .map(), unlike .forEach(), has a return value
}

console.log(Array.prototype)

var someNums = [10,20,3,4]

// squareOne is a callback that we will give to mapOver. it takes in an array element, and returns a transformation of it.
var squareOne = function(num) {
    return num * num
}
var newNums = someNums.mapOver(squareOne) // note that .mapOver(), unlike .forEach(), *returns something*. specifically, it returns a new array. 

console.log(newNums)
console.log('')
// [100,400,9,16]

var names = ['notsup simble', 'danny noms', 'kristine pristine']


// nameToObj is a callback that we will give to mapOver. it takes in an array element, and returns a transformation of it.
var nameToObj = function(name) {
    var nameParts = name.split(' ') // ['first','last']
    return {
        firstName: nameParts[0],
        lastName: nameParts[1]
    }
}

var nameObjs = names.mapOver(nameToObj)

console.log(nameObjs)
// [
//     {firstName: 'notsup', lastName: 'simble'},
//     {firstName: 'danny', lastName: 'noms'},
//     {firstName: 'kristine', lastName: 'pristine'}
// ]