Dynamic Arrays

**wesleytabaka** · 11-04-2007, 06:44 PM

Does anyone know a way to make a javascript function that will print an array in a similar way to this:

Code:

function list(field){
     var nissan=new Array();
     nissan[0]="Quest";
     nissan[1]="Versa";
     nissan[2]="Altima";
 
     var mitsubishi=new Array();
     mitsubishi[0]="Eclipse";
     mitsubishi[1]="Lancer";
     mitsubishi[2]="Outlander";

     for(x=0; x<field.length; x++){
           document.write(field[x] + "<br />");
     }
}

If I were to run the function list("nissan"), It would, in theory, write:
Quest
Versa
Altima

But, it doesn't. Instead it writes:
n
i
s
s
a
n

It thinks the field parameter is a string, which is what it is. But I want it to behave as a variable name, to be able to refer to the nissan and mitsubishi arrays. How can I make the parameter refer to those arrays instead of act as a string?

**Trinithis** · 11-04-2007, 06:49 PM

Code:

var nissan=new Array();
nissan[0]="Quest";
nissan[1]="Versa";
nissan[2]="Altima";
 
var mitsubishi=new Array();
mitsubishi[0]="Eclipse";
mitsubishi[1]="Lancer";
mitsubishi[2]="Outlander";

function list(field) {
     for(x=0; x<field.length; x++) document.write(field[x] + "<br />");
}

Or better yet

Code:

var nissan = ["Quest", "Versa", "Altima"];
 
var mitsubishi = ["Eclipse", "Lancer", "Outlander"];

function list(field) {
     for(x=0; x<field.length; x++) document.write(field[x] + "<br />");
}

If you want to define the arrays inside the function, then you have to use a control statement

Code:

function list(field) {
   field = field.toLowerCase();
   var nissan = ["Quest", "Versa", "Altima"];
   var mitsubishi = ["Eclipse", "Lancer", "Outlander"];
   switch(field) {
   case "nissan":
      field = nissan;
      break;
   case "mitsubishi":
      field = mitsubishi;
      break;
   default:
      field = ["Brand not found"];
   }
   for(x=0; x<field.length; x++) document.write(field[x] + "<br />");
}

The first two don't take a string, but the var name. The last takes a string.

**wesleytabaka** · 11-04-2007, 07:59 PM

Terrific! Thanks so much!

I didn't think the solution would be so simple.

**jscheuer1** · 11-04-2007, 08:12 PM

How 'bout:

Code:

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title></title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<script type="text/javascript">
     list.nissan=["Quest","Versa","Altima"];
     list.mitsubishi=["Eclipse","Lancer","Outlander"];
function list(field){
     for(var x=0; x<list[field].length; x++)
           document.write(list[field][x] + "<br>");
}
</script>
</head>
<body>
<script type="text/javascript">
list('nissan');
</script>
</body>
</html>

**Twey** · 11-04-2007, 08:34 PM

Academically:

Code:

<script type="text/javascript">
  var listCars = (function(listsObj) {
    return function(field) {
      for(var i = 0, a = listsObj[field] || [], n = a.length; i < n; ++i)
        document.write(a[i] + "<br>");
    };
  })({
    mitsubishi: ["Eclipse", "Lancer", "Outlander"],
    nissan: ["Quest", "Versa", "Altima"]
  });
</script>

However, note that document.write() is no longer a very good idea, and this is an abuse of <br>. Instead, you could have the function return a list element:

Code:

<script type="text/javascript">
  var listCars = (function(listsObj) {
    return function(field) {
      for(var i = 0, r = document.createElement("ul"), a = listsObj[field] || [], n = a.length; i < n; ++i)
        r.appendChild(document.createElement("li")).appendChild(document.createTextNode(a[i]));
      return r;
    };
  })({
    mitsubishi: ["Eclipse", "Lancer", "Outlander"],
    nissan: ["Quest", "Versa", "Altima"]
  });
</script>

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