Multi-dimensional associative arrays in JavaScript

There is the following query results: (key1 and key2 could be any text)

id   key1     key2     value

1    fred     apple    2
2    mary     orange   10
3    fred     banana   7
4    fred     orange   4
5    sarah    melon    5
...

and I wish to store the data in a grid (maybe as an array) looping all the records like this:

         apple    orange   banana  melon
fred        2        4         7     -
mary        -        10        -     -
sarah       -        -         -     5

In PHP this would be really easy, using associative arrays:

$result['fred']['apple'] = 2;

But in JavaScript associative arrays like this doesn't work. After reading tons of tutorial, all I could get was this:

arr=[];
arr[1]['apple'] = 2;

but arr['fred']['apple'] = 2; doesn't work. I tried arrays of objects, but objects properties can't be free text. The more I was reading tutorials, the more I got confused...

Any idea is welcome :)

Solution 1:

Just use a regular JavaScript object, which would 'read' the same way as your associative arrays. You have to remember to initialize them first as well.

var obj = {};

obj['fred'] = {};
if('fred' in obj ){ } // can check for the presence of 'fred'
if(obj.fred) { } // also checks for presence of 'fred'
if(obj['fred']) { } // also checks for presence of 'fred'

// The following statements would all work
obj['fred']['apples'] = 1;
obj.fred.apples = 1;
obj['fred'].apples = 1;

// or build or initialize the structure outright
var obj = { fred: { apples: 1, oranges: 2 }, alice: { lemons: 1 } };

If you're looking over values, you might have something that looks like this:

var people = ['fred', 'alice'];
var fruit = ['apples', 'lemons'];

var grid = {};
for(var i = 0; i < people.length; i++){
    var name = people[i];
    if(name in grid == false){
        grid[name] = {}; // must initialize the sub-object, otherwise will get 'undefined' errors
    }

    for(var j = 0; j < fruit.length; j++){
        var fruitName = fruit[j];
        grid[name][fruitName] = 0;
    }
}

Solution 2:

If it doesn't have to be an array, you can create a "multidimensional" JS object...

<script type="text/javascript">
var myObj = { 
    fred: { apples: 2, oranges: 4, bananas: 7, melons: 0 }, 
    mary: { apples: 0, oranges: 10, bananas: 0, melons: 0 }, 
    sarah: { apples: 0, oranges: 0, bananas: 0, melons: 5 } 
}

document.write(myObj['fred']['apples']);
</script>

Solution 3:

Javascript is flexible:

var arr = {
  "fred": {"apple": 2, "orange": 4},
  "mary": {}
  //etc, etc
};

alert(arr.fred.orange);
alert(arr["fred"]["orange"]);
for (key in arr.fred)
    alert(key + ": " + arr.fred[key]);