JavaScript - Arbeiten mit Objekten

Objekte statt Arrays

Quelle: http://stackoverflow.com/questions/4329092/multi-dimensional-associative-arrays-in-javascript (Zugriff 07-2013)

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

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;
    }
}