Help in Merging two objects with condition

[bakman2]

After the join node use a function node with something like:

const input = msg.payload

const dataMap = {};
input.speed.forEach(item => {
    dataMap[item.Date] = item;
});

input.availability.forEach(availabilityItem => {
    const speedItem = dataMap[availabilityItem.Date];
    if (speedItem) {
        Object.assign(availabilityItem, speedItem);
    }
});

msg.payload = input.availability;
return msg;

note the correct terminology is 'merge' for this use case.