depth_merge.js

var util = exports || {};

util.mergeDeep = function(A, B, depth) {
    var forever = depth == null;
    for (var p in B) {
        if (B[p] != null && B[p].constructor == Object && (forever || depth > 0)) {
            A[p] = util.mergeDeep(A.hasOwnProperty(p) ? A[p] : {}, B[p], forever ? null : depth - 1);
        } else {
            A[p] = B[p];
        }
    }
    return A;
};

util.merge = function(A, B) {
    return util.mergeDeep(A, B, 0);
};

util.mergeCopy = function(A, B, depth) {
    var A_copy = util.mergeDeep({}, A);
    return util.mergeDeep(A_copy, B, depth);
};