Array search in Javascript not working

Question

I have the following data structure:

var map_neighbours = [{
    "Alaska": ["UstKamchatsk", "Yukon"]
}, {
    "Algeria": ["Chad", "Egypt", "SierraLeone", "Spain"]
}, {
    "AntarticWildlifeTerritory": ["AustralianAntarticTerritory", "SouthAfricanAntarticTerritory"]
}, .....]

The user selects a region via the page, I want to loop through this structure, find the region, then loop through the sub-regions (in the corresponding position).

So for example, for Algeria I want to get "Chad", "Egypt", "SierraLeone", "Spain" one by one out of a loop.

I have tried a few variation of this without success (region is supplied by the user as mentioned above):

var neighbourArray = map_neighbours[region];

$.each(neighbourArray, function(idx, val) {

    console.log("Neighbours= " + neighbourArray[region][idx]);

});

or

$.each(map_neighbours, function(outer, val) {

    if (map_neighbours[outer] == region) {

        neighbourArray = (map_neighbours[outer][]);

        $.each(neighbourArray, function(inner, val) {

            console.log("Neighbours= " + neighbourArray[outer][inner]);

        });

     );

};

Thanks for any advice.

Is that = > supposed to be there, or is it supposed to be a :? — Spencer Wieczorek
– Spencer Wieczorek, Commented Oct 8, 2015 at 3:25

Arun P Johny · Accepted Answer · 2015-10-08 03:25:52Z

With your current structure you need to iterate over the array and see whether the item has the input value as a key like

var map_neighbours = [{
  "Alaska": ["UstKamchatsk", "Yukon"]
}, {
  "Algeria": ["Chad", "Egypt", "SierraLeone", "Spain"]
}, {
  "AntarticWildlifeTerritory": ["AustralianAntarticTerritory", "SouthAfricanAntarticTerritory"]
}];

var input = 'Algeria',
  result;
$.each(map_neighbours, function(i, item) {
  if (item[input]) {
    result = item[input];
    return false;
  }
})

if (result) {
  snippet.log(JSON.stringify(result));
} else {
  snippet.log('not found')
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<!-- Provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>

But a much better structure to handle the case is to use a key value object instead of an array of objects

var map_neighbours = {
  "Alaska": ["UstKamchatsk", "Yukon"],
  "Algeria": ["Chad", "Egypt", "SierraLeone", "Spain"],
  "AntarticWildlifeTerritory": ["AustralianAntarticTerritory", "SouthAfricanAntarticTerritory"]
};

var input = 'Algeria',
  result = map_neighbours[input];

if (result) {
  snippet.log(JSON.stringify(result));
} else {
  snippet.log('not found')
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<!-- Provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>

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