JSFiddle - React, Tailwind, and code Playground

by BeNdErR

JavaScript

var allDataJson = [{
    "Researchers": "Laura, Mikael",
    "Year": "2015"
}, {
    "Researchers": "Mikko",
    "Year": "2013",
}, {
    "Researchers": "Harri",
    "Year": "2015"
}];

var count = {};
for (var x = 0; x < allDataJson.length; x++) {
    var current = allDataJson[x];
    if (!count[current["Year"]]) count[current["Year"]] = 1;
    else
        count[current["Year"]] = count[current["Year"]] + 1;
}
console.log(count);