javascript - Create a new array adding duplicate values together -

i have 2 dimensional array:

[[bourbon, 2], [bourbon, 1],[scotch, 2]] 

i end new array consolidates duplicates array become

 [[bourbon, 3], [scotch, 2]] 

here how create array:

    for(var i=0; i< data.length; i++){          var typew = string(data[i].doc.type);          var valueasnumber = parseint(data[i].doc.bottle);          typeofwhiskey[j,i] = [typew,valueasnumber];          j++;     }    

i have tried check unique values with:if(typeofwhiskey.indexof(typew ) > -1){

however stuck. in example 'typew' string value 'bourbon', or 'scotch' example, 'valueasnumber' 2 or 1 based on example provided. not have create , iterate through whole array again because feel inefficient. think close not sure how proceed. thanks

this work:

var source = [['bourbon', 2], ['bourbon', 1],['scotch', 2]]; var hash = {}; var consolidated = [];  source.foreach(function(item) {      hash[item[0]] = (hash[item[0]] || 0) + item[1]; });  object.keys(hash).foreach(function(key) {      consolidated.push([key, hash[key]]); }); 

jsfiddle