JavaScript function returning an object

Question

I m taking some JavaScript jQuery lessons at codecademy com  Normally the lessons provide answers or hints  but for this one it doesn t give any help and I m a little confused by the instructions    It says to make the function makeGamePlayer return an object with three keys      First  the object creator function makeGamePlayer name totalScore gamesPlayed          should return an object with three keys         name        totalScore        gamesPlayed     I m not sure if i should be doing this    First  the object creator function makeGamePlayer name totalScore gamesPlayed          should return an object with three keys         name        totalScore        gamesPlayed           this name    name           this totalScore   totalScore           this gamesPlayed   gamesPlayed      or something like this     First  the object creator     function makeGamePlayer name totalScore gamesPlayed              should return an object with three keys             name            totalScore            gamesPlayed           var obj                  this name    name               this totalScore   totalScore               this gamesPlayed   gamesPlayed                      I have to be able to modify the properties of the object after its created

User · Answer

The latest way to do this with ES2016 JavaScript  let makeGamePlayer    name  totalScore  gamesPlayed    gt         name      totalScore      gamesPlayed

User · Answer

I would take those directions to mean     function makeGamePlayer name totalScore gamesPlayed              should return an object with three keys             name            totalScore            gamesPlayed           var obj        note you don t use   in an object definition               name   name                totalScore   totalScore                gamesPlayed   gamesPlayed                      return obj

User · Answer

You can simply do it like this with an object literal   function makeGamePlayer name totalScore gamesPlayed        return           name  name          totalscore  totalScore          gamesPlayed  gamesPlayed

User · Answer

Both styles  with a touch of tweaking  would work   The first method uses a Javascript Constructor  which like most things has pros and cons       By convention  constructors start with an upper case letter function MakePerson name age         The magic variable  this  is set by the Javascript engine and points to a newly created object that is ours    this name   name    this age   age    this occupation    Hobo     var jeremy   new MakePerson  Jeremy   800     On the other hand  your other method is called the  Revealing Closure Pattern  if I recall correctly   function makePerson name2  age2      var name   name2    var age   age2     return       name  name      age  age

User · Answer

In JavaScript  most functions are both callable and instantiable  they have both a   Call   and   Construct   internal methods   As callable objects  you can use parentheses to call them  optionally passing some arguments  As a result of the call  the function can return a value   var player   makeGamePlayer  John Smith   15  3     The code above calls function makeGamePlayer and stores the returned value in the variable player  In this case  you may want to define the function like this   function makeGamePlayer name  totalScore  gamesPlayed         Define desired object   var obj         name   name      totalScore  totalScore      gamesPlayed  gamesPlayed           Return it   return obj      Additionally  when you call a function you are also passing an additional argument under the hood  which determines the value of this inside the function  In the case above  since makeGamePlayer is not called as a method  the this value will be the global object in sloppy mode  or undefined in strict mode   As constructors  you can use the new operator to instantiate them  This operator uses the   Construct   internal method  only available in constructors   which does something like this    Creates a new object which inherits from the  prototype of the constructor Calls the constructor passing this object as the this value It returns the value returned by the constructor if it s an object  or the object created at step 1 otherwise    var player   new GamePlayer  John Smith   15  3     The code above creates an instance of GamePlayer and stores the returned value in the variable player  In this case  you may want to define the function like this   function GamePlayer name totalScore gamesPlayed          this  is the instance which is currently being created   this name    name    this totalScore   totalScore    this gamesPlayed   gamesPlayed       No need to return  but you can use  return this   if you want     By convention  constructor names begin with an uppercase letter   The advantage of using constructors is that the instances inherit from GamePlayer prototype  Then  you can define properties there and make them available in all instances

[javascript] JavaScript: function returning an object

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