Merging objects (associative arrays)

Question

What’s the best/standard way of merging two associative arrays in JavaScript? Does everyone just do it by rolling their own for loop?

Answer 1

do you want to overwrite a property if the names are the same but the values are not?

And do you want to permanently change one of the original objects,

or do you want a new merged object returned?

function mergedObject(obj1, obj2, force){
    for(var p in obj1) this[p]= obj1[p];
    for(var p in obj2){
        if(obj2.hasOwnProperty(p)){
            if(force || this[p]=== undefined) this[p]= obj2[p];
            else{
                n= 2;
                while(this[p+n]!== undefined)++n;
                this[p+n]= obj2[p];
            }
        }
    }
}