lib/util.js
function (target, source) {
        var key;

        for (key in source) {
            if (source.hasOwnProperty(key) && !_.isUndefined(source[key])) {
                target[key] = source[key];
            }
        }

        return target;
    }
function (target, source) {
        var key;

        for (key in source) {
            if (source.hasOwnProperty(key) && !_.isUndefined(source[key])) {
                target[key] = source[key];
            }
        }

        return target;
    }
function ( target , source ) { var key ; for ( key in source ) { if ( source . hasOwnProperty ( key ) && ! _ . isUndefined ( source [ key ] ) ) { target [ key ] = source [ key ] ; } } return target ; }
Merges defined keys from the target object onto the source object.

@param {Object} target
@param {Object} source
@returns {Object}
Merges defined keys from the target object onto the source object .