Combine json arrays by key, javascript

Two one-liners:

with lodash:

res = _(json1).concat(json2).groupBy('id').map(_.spread(_.assign)).value();

in ES2015:

res = json2.map(x => Object.assign(x, json1.find(y => y.id == x.id)));

ES2015 georg's answer works great;

    json1 = [
    {id:1, test: 0},
    {id:2, test: 0},
    {id:3, test: 0},
    {id:4, test: 0},
    {id:5, test: 0}
];

json2 = [
    {id:1, test: 1},
    {id:3, test: 1},
    {id:5, test: 1}
];

json1.map(x => Object.assign(x, json2.find(y => y.id == x.id)));

result:

{id:1, test: 1},
{id:2, test: 0},
{id:3, test: 1},
{id:4, test: 0},
{id:5, test: 1}