How would I combine these 2 similar functions?

Question

I have created two functions that run a similar set of IF statements, one shows the cost of a game, the other its name. I have used "onclick" to display both values in my form. It all works but suffers from bloat. Is there a way to combine both functions to shorten the script?

        function GameTitle() {
var textboxValue = document.getElementById("game_id").value;
    var message;
    if (textboxValue == 1) {
        message = "Fantasy World";
    } else if (textboxValue == 2) {
        message = "Sir Wags A Lot";
    } else if (textboxValue == 3) {
        message = "Take a Path";
    } else if (textboxValue == 4) {
        message = "River Clean Up";
    } else if (textboxValue == 5) {
        message = "PinBall";
    } else if (textboxValue == 6) {
        message = "Ghost girl";
    } else if (textboxValue == 7) {
        message = "Dress Up";
    } else if (textboxValue == 8) {
        message = "Where is my hat?";
    } else {
        message = "Invalid ID";
    }
document.getElementById("game_title").value = message;
}

//Display price of Game
    function Cost() {
var textboxValue = document.getElementById("game_id").value;
    var cost;
    if (textboxValue == 1) {
        cost = "0.99";
    } else if (textboxValue == 2) {
        cost = "0.99";
    } else if (textboxValue == 3) {
        cost = "1.99";
    } else if (textboxValue == 4) {
        cost = "1.99";
    } else if (textboxValue == 5) {
        cost = "3.99";
    } else if (textboxValue == 6) {
        cost = "3.99";
    } else if (textboxValue == 7) {
        cost = "1.99";
    } else if (textboxValue == 8) {
        cost = "1.99";
    } else {
        cost = "Invalid ID";
    }
document.getElementById("cost").value = cost;
}

Answer 1

You should use an array of objects for this

var games = [
 {
  message : "Fantasy World",
  cost : 0.99
 },
 {
  message : "Sir Wags A Lot",
  cost : 0.99
 },
 {
  message : "Take a Path",
  cost : 1.99
 },
 {
  message : "River Clean Up",
  cost : 1.99
 },
 {
  message : "PinBall",
  cost : 3.99
 },
 {
  message : "Ghost girl",
  cost : 3.99
 },
 {
  message : "Dress Up",
  cost : 1.99
 },
 {
  message : "Where is my hat?",
  cost : 1.99
 }
];

And then in your function you can accept and id, reference its index in the array (offset by 1 for 0 based) and use that object.

function Display(){
 var textboxValue = parseInt(document.getElementById("game_id").value,10);
 document.getElementById("game_title").value = 
  textboxValue-1 < games.length ? games[textboxValue-1].message : "Invalid ID";
 document.getElementById("cost").value = 
  textboxValue-1 < games.length ? games[textboxValue-1].cost : "Invalid ID";
}

Answer 2

You basically want to make the update to both fields at once. Since your driving variable is one ( game_id ) for both factors (title and cost), then you should make the update to those two fields at once. So, something like the following would do:

  function updateGameTitleAndCost() { var textboxValue = document.getElementById("game_id").value; var message, cost; if (textboxValue == 1) { message = "Fantasy World"; cost = "0.99"; } else if (textboxValue == 2) { message = "Sir Wags A Lot"; cost = "0.99"; } else if (textboxValue == 3) { message = "Take a Path"; cost = "1.99"; } else if (textboxValue == 4) { message = "River Clean Up"; cost = "1.99"; } else if (textboxValue == 5) { message = "PinBall"; cost = "3.99"; } else if (textboxValue == 6) { message = "Ghost girl"; cost = "3.99"; } else if (textboxValue == 7) { message = "Dress Up"; cost = "1.99"; } else if (textboxValue == 8) { message = "Where is my hat?"; cost = "1.99"; } else { message = "Invalid ID"; cost = "Invalid ID"; } document.getElementById("game_title").value = message; document.getElementById("cost").value = cost; } 

Answer 3

You can replace IFs with simple map:

values = {
  "1": "0.99",
  "2": "0.99",
  ...
}

Then call it with:

cost = values[textboxValues]

So you just need 2 maps for you example. If the cost is not found with the line above, it means it should be "Invalid ID" value.

Update:

values = {
  "1": {
    cost: "0.99",
    name: "Sir Bunny Hopings"
  },
  "2": {..},
  ...
  }

Game = function() {
  var i = document.getElementById("game_id").value,
      game;

  game = values[id] || {cost: "Invalid ID", name: "Invalid iD"};

  document.getElementById("cost").value = game.cost;
  document.getElementById("game_title").value = game.name;
}