Javascript string to object reference (without eval() or indexes)

Question

I've seen quite some related questions and google results, but none seem to match my problem.

I'm getting a string "header.h2" which I want to contencate to 'var objects'. So I want objects.header.h2 (which contains more hash data).

However, I don't want to use eval() or the often suggested buttons[] for the obvious reason that buttons[header.h2] won't work and I would need buttons[header][h2].

So how can I remain the object notation, or in the worst case, solve my problem?

Answer 1

Just a quick sketch of a possible way:

Your data:

var data = [
    {foo: 1, bar: 2, foobar: [
        'a', 'b', 'c'
    ]},
    {foo: 1, bar: 2, foobar: [
        'd', 'e', 'f'
    ]},
    {foo: 1, bar: 2, foobar: [
        'g', 'h', 'i'
    ]}
];

var accessor = '1.foobar.2';

Using a helper function:

function helper(data, accessor) {
    var keys = accessor.split('.'),
        result = data;

    while (keys.length > 0) {
        var key = keys.shift();
        if (typeof result[key] !== 'undefined') {
            result = result[key];
        }
        else {
            result = null;
            break;
        }
    }

    return result;
}

Or making it available to all objects: (personally, I don't like this...)

Object.prototype.access = function (accessor) {
    var keys = accessor.split('.'),
        result = this;

    while (keys.length > 0) {
        var key = keys.shift();
        if (typeof result[key] !== 'undefined') {
            result = result[key];
        }
        else {
            result = null;
            break;
        }
    }

    return result;
};

Debug output:

console.log(
    helper(data, accessor), // will return 'f'
    data.access(accessor) // will return 'f'
);