Extract one class from global LULC in google earth engine

Question

I am trying to extract one LULC class (e.g. cropland) for the entire globe from the MODIS global lulc. How it can be done? Code I am using to display global lulc is:

    var cover = ee.Image('MODIS/051/MCD12Q1/2012_01_01').select('Land_Cover_Type_1');
    var cover_palette = [
    'aec3d4', // water
    '152106', '225129', '369b47', '30eb5b', '387242', // forest
    '6a2325', 'c3aa69', 'b76031', 'd9903d', '91af40',  // shrub, grass
    '111149', // wetlands
    'cdb33b', // croplands
    'cc0013', // urban
    '33280d', // crop mosaic
    'd7cdcc', // snow and ice
    'f7e084', // barren
    '6f6f6f'  // tundra
     ];

    Map.addLayer(cover, {min: 0, max: 17, palette: cover_palette },  
                'Land Cover classification');

Answer 1

There is a lot of ways to do this. If you want to preserve class ID, you need to mask the desired class. For example:

var crop_mask = cover.eq(13); // create a mask for crops
var crop = cover.mask(crop_mask); // mask it
Map.addLayer(crop,{},'Crops');

---

As Rodrigo E. Principe and Nicholas Clinton suggest:

var crop = cover.updateMask(cover.eq(13)); // mask it
Map.addLayer(crop,{},'Crops');