Question

I have an array in JS and need to look up the data by doing checks against it, but am wondering how i do it =/

My array is structured like this :

//global array spritea
var listObj = {
    id: uid,
    data: [
        abposx,
        abposy,
        (abposx+imgwidth),
        (abposy-imgheight)
    ]
};                  

spritea.push(listObj);

This is in a loop so an example of the array is :

spritea = [
    {
        id: "135", 
        data: [9,129,345, 687]
    },
    {
        id: "239", 
        data: [596,382,0,687,33467]
    }
];

So what im trying to do is this:

Find

id where x is > data[0] && y > data[1] && x < data[2] && y < data[3]

And then it returns the id ?

Any one know how to do that? Its really confusing me =/

Answer 1

It’s going to be inefficient for large arrays since it’s O(n) (simple linear search), but should do the trick:

spritea = [
    {
        id: "135", 
        data: [9,129,345, 687]
    },
    {
        id: "239", 
        data: [596,382,0,687,33467]
    }
];

function searchSprites(sprites, x, y) {
    var matches = [],
        i = 0,
        data = null;
    for (i = 0; i < sprites.length; ++i) {
        data = sprites[i].data;
        if (x > data[0] && y > data[1] && x < data[2] && y < data[3]) {
            matches.push(sprites[i].id);
        }
    }
    return matches;
}
​

It’s untested, but should work. Also, if you need better performance, you’re going to have to index the data somehow.

Edit: jsfiddle: http://jsfiddle.net/mP6cH/3/