Lodash create collection from duplicate object keys

Question

I have the following structure:

var output = [{
    \"article\": \"BlahBlah\",
    \"title\": \"Another blah\"
}, {
    \"article\": \"BlahBlah\",
    \"titl         


        

Answer 1

A proposal in plain Javascript

It uses a IIFE (Immediate Invoked Function Expression) for using private variables and for collecting the return values in an array.

Beside that it uses a hash table for the reference to the right array item.

var output = [{ article: "BlahBlah", title: "Another blah" }, { article: "BlahBlah", title: "Return of the blah" }, { article: "BlahBlah2", title: "The blah strikes back" }, { article: "BlahBlah2", title: "The blahfather" }],
    newOutput = function (data) {
        var r = [];
        data.forEach(function (a) {
            if (!this[a.article]) {
                this[a.article] = { article: a.article, titles: [] };
                r.push(this[a.article]);
            }
            this[a.article].titles.push(a.title);
        }, Object.create(null));
        return r;
    }(output);
        
console.log(newOutput);