Javascript number of object by different property values in array -

best way count number of objects in array different object property p values.

function([{"p":"a"},{"p":"b"},{"p":"a"}]){     // code } // in case return 2 

you can use array.prototype.filter() keep values want. in case, must create variable temp storing duplicate values , within filter function returns true if not exist in case. have new array of unique values.

var arr = [{"p":"a"},{"p":"b"},{"p":"a"}], temp = [];    var arruniques = arr.filter(function(obj){    return temp.indexof(obj.p) === -1 ? !!temp.push(obj.p) : false  });    alert(arruniques.length)