var array = [{'id':1, 'Color':'blue'},
             {'id':2, 'Color':'orange'},
             {'id':3, 'Color':'green'},
             {'id':4, 'Color':'blue'} ];

var myFilter = array.filter(function (item) {
                    return item.Color === 'blue';
                });

var result = array.filter(function(item) {
    return item.Color === 'blue';
}).map(function(item) {
    return item.id;
});

console.log(result)
# [1, 4]

var result = _.chain(array)
    .filter(function(item) {
        return item.Color === 'blue';
    })
    .pluck("id")
    .value();

console.log(result);
# [1, 4]

var result = _.chain(array)
    .where({Color: 'blue'})
    .pluck("id")
    .value();

console.log(result)
# [1, 4]

console.log(_.pluck(_.where(array, {Color: 'blue'}), "id"));
# [1, 4]

var result = [];
for (var i = 0; i < array.length; i += 1) {
    if (array[i].Color === "blue") {
        result.push(array[i].id);
    }
}
console.log(result);
# [1, 4]