Multi-dimensional associative arrays in JavaScript

Question

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 :)

Answer 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;     } } 

Answer 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>