javascript - Output a result array with a grouped count of unique elements for a given array -

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• array value count javascript 4 answers

if have array how can loop through , push counts a new array?
wlcomed!

    var products = [     ['product a'],     ['product a'],     ['product a'],     ['product a'],     ['product a'],     ['product b'],     ['product b'],     ['product b'],     ['product b'],     ['product b'],     ['product b'],     ['product b'],     ['product b'],         ['product b'],     ['old product b'],     ['old product b'],     ['old product b'],     ['old product b'],     ['old product b'],     ['old product]          ]; 

end goal :

        var uniqueproducts = [     ['product a',5],     ['product b',6],     ['old product b',9]      ]; 

accomplished doing simple coding expected result. http://jsfiddle.net/y9a8l/

function groupby(arrparam) {     var result = [];     var lastitem = null;     var item = null;     var index = -1;     (var = 0; < arrparam.length ; i++ )     {         item = arrparam[i][0];         if (lastitem != item)         {             result.push([item,1]);             index++;         }         else         {             result[index][1]++;         }         lastitem = item     }     console.log(result) } groupby(products);