// *** before: ***
var entries = [["a", 1], ["b", 2]];
var obj = {};
entries.forEach(function (entry) {
    obj[entry[0]] = entry[1];
});

// *** in version ES2019: ***
const entries = [["a", 1], ["b", 2]];
const obj = Object.fromEntries(entries);

const params = new URLSearchParams("a=1&b=2");
const query = Object.fromEntries(params);