Question

185

Search multi-dimensional array JavaScript

rated 0 times [ 188] [ 3] / answers: 1 / hits: 101640 / 13 Years ago, tue, january 10, 2012, 12:00:00

I have an array which looks like this :

selected_products[0]=[r1,7up,61,Albertsons]

selected_products[1]=[r3, Arrowhead,78,Arrowhead ]

selected_products[2]=[r8, Betty Crocker Cake Mix (Variety),109,Arrowhead ]

...

how can I search for an item in this array according to the first entry in each item (r1,r2,..)
the array is huge I am looking for a fast an effective way to get results from this array
I used the JQuery function jQuery.inArray but it couldn't find any thing in my array , I used it this way :

alert($.inArray([r1,7up,61,Albertsons],selected_products))// it returns -1

alert($.inArray(r1,selected_products))//this also returns -1

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jalyn

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1 Year ago

answered 13 Years ago draven · Accepted Answer

If you want it to be fast, you'll want a for loop so that you can break the loop when the match is found.

var result;

for( var i = 0, len = selected_products.length; i < len; i++ ) {

    if( selected_products[i][0] === 'r1' ) {

        result = selected_products[i];

        break;

    }

}

Of course this assumes there's only one match.

If there's more than one, then you could use $.grep if you want jQuery:

var result = $.grep(selected_products, function(v,i) {

    return v[0] === 'r1';

});

This will give you a new Array that is a subset of the matched items.

In a similar manner, you could use Array.prototype.filter, if you only support modern JavaScript environments.

var result = selected_products.filter(function(v,i) {

    return v[0] === 'r1';

});

One other solution would be to create an object where the keys are the rn items. This should give you a very fast lookup table.

var r_table = {};

for( var i = 0, len = selected_products.length; i < len; i++ ) {

    r_table[selected_products[i][0]] = selected_products[i];

}

Then do your lookups like this:

r_table.r4;

Again this assumes that there are no duplicate rn items.