MapsInJS

MapsInJS.js

// Array you wanna do the operation on
const peopleArray = [ {Name: "Tim", BankBalance: 10}, 
                {Name: "Leo", BankBalance: 20}, 
                {Name: "Sam", BankBalance: 30} ];

// calling the Map function and having it return its value into 
// reformattedArray. Where "obj" represents each object in the 
// peopleArray

let reformattedArray = peopleArray.map((obj) =>{ 
    let newObj = {};
    newObj.Name = "Mr." + obj.Name;
    newObj.BankBalance = obj.BankBalance * 1000;
    return newObj;
});

console.log(reformattedArray);
// "reformattedArray" is now: [ { Name: 'Mr.Tim', BankBalance: 10000 },
//                              { Name: 'Mr.Leo', BankBalance: 20000 },
//                              { Name: 'Mr.Sam', BankBalance: 30000 } ]

// you can also get another parameter that is passed in. Known as the index 
// of the object in the old array (peopleArray in this case)
reformattedArray = peopleArray.map((obj, index) =>{ 
    let newObj = {};
    newObj.MyIndex = index;
    newObj.Name = "Mr." + obj.Name;
    newObj.BankBalance = obj.BankBalance * 1000;
    return newObj;
});

console.log(reformattedArray);
// "reformattedArray" is now:[ { MyIndex: 0, Name: 'Mr.Tim', BankBalance: 10000 },
//                             { MyIndex: 1, Name: 'Mr.Leo', BankBalance: 20000 },
//                             { MyIndex: 2, Name: 'Mr.Sam', BankBalance: 30000 } ]