JavaScript merging objects by id

Question

What\'s the correct way to merge two arrays in Javascript?

I\'ve got two arrays (for example):

var a1 = [{ id : 1, name : \"test\"}, { id : 2, name :         


        

Answer 1

You can write a simple object merging function like this

function mergeObject(cake, icing) {
    var icedCake = {}, ingredient;
    for (ingredient in cake)
        icedCake[ingredient] = cake[ingredient];
    for (ingredient in icing)
        icedCake[ingredient] = icing[ingredient];
    return icedCake;
}

Next, you need to do use a double-loop to apply it to your data structre

var i, j, a3 = a1.slice();
for (i = 0; i < a2.length; ++i)                // for each item in a2
    for (j = 0; i < a3.length; ++i)            // look at items in other array
        if (a2[i]['id'] === a3[j]['id'])       // if matching id
            a3[j] = mergeObject(a3[j], a2[i]); // merge

You can also use mergeObject as a simple clone, too, by passing one parameter as an empty object.