javascript - Underscore JS: get 5 items per category -

i have 5 items per category. let's have array this:

[   {product_name: "test", supplier: "1"}   {product_name: "test", supplier: "1"}   {product_name: "test", supplier: "1"}   {product_name: "test", supplier: "1"}   {product_name: "test", supplier: "1"}   {product_name: "test", supplier: "1"}   {product_name: "test", supplier: "2"}   {product_name: "test", supplier: "2"}   {product_name: "test", supplier: "2"}   {product_name: "test", supplier: "3"}   {product_name: "test", supplier: "3"}   {product_name: "test", supplier: "3"}   {product_name: "test", supplier: "3"}   ] 

of each supplier have first 5 products. don't have clue how that. has?

my current code:

var formattedproducts = _(products).map( function( product ) {      var pr =  product.datavalues;     var endtime = pr.end_datetime;      return pr; }); 

this works me

var data = [   {product_name: "test", supplier: "1"},   {product_name: "test", supplier: "1"},   {product_name: "test", supplier: "1"},   {product_name: "test", supplier: "1"},   {product_name: "test", supplier: "1"},   {product_name: "test", supplier: "1"},   {product_name: "test", supplier: "2"},   {product_name: "test", supplier: "2"},   {product_name: "test", supplier: "2"},   {product_name: "test", supplier: "3"},   {product_name: "test", supplier: "3"},   {product_name: "test", supplier: "3"},   {product_name: "test", supplier: "3"}   ] 

1) first group elements according supplier.

2) each group first 5 elements & con-cat result array.

var result = []; var groups = _.groupby(data,function (item) {     return item.supplier; });   _.each(groups,function(value){     result = result.concat(_.first(value,5)); })  console.log(result); 

demo