Question

var params = {
    search: {
        make: "",
        model: ""
    }
}

function setVariable() {
    var value = "BMW";
    var key = "search.make";
    var arr = key.split(".");    //eg. ["search", "make"]
    params[arr[0]][arr[1]] = value;   // this works, but how do you
                                      // do it with unknown arr[] length?
}

How do I do this with an unknown arr[] length?

I have surmised that I probably need to do a recursive call, maybe passing something like arr.slice(1) within the function, but I have not been able to figure out what that should look like.

Answer 1

var params = {
    search: {
        make: "",
        model: "",
        whatever: {
            foo: {
                bar: {
                    moo: 123,
                    meow: 'xyz'
                }
            }
        }
    }
};

function updatePath(obj, path, value) {
    var parts = path.split('.');
    var i, tmp;
    for(i = 0; i < parts.length; i++) {
        tmp = obj[parts[i]];
        if(value !== undefined && i == parts.length - 1) {
            tmp = obj[parts[i]] = value;
        }
        else if(tmp === undefined) {
            tmp = obj[parts[i]] = {};
        }
        obj = tmp;
    }
    return obj;
}

Demo:

> updatePath(params, 'search.whatever.foo.bar')
{ moo: 123, meow: 'xyz' }
> updatePath(params, 'search.whatever.foo.bar.moo')
123
> updatePath(params, 'search.whatever.foo.bar.moo', 'test')
'test'
> updatePath(params, 'search.whatever.foo.bar.moo')
'test'
> updatePath(params, 'search.whatever.foo.bar')
{ moo: 'test', meow: 'xyz' }
> updatePath(params, 'search.whatever.foo.bar.x.y.z', 'hi')
'hi'
> updatePath(params, 'search.whatever.foo.bar.x')
{ y: { z: 'hi' } }
> updatePath(params, 'search.whatever.foo.bar')
{ moo: 'test',
  meow: 'xyz',
  x: { y: { z: 'hi' } } }
>