backbone-model-unset.js

    // Improved unset for multiple values.
    unset: function(attr, options){
        var unset = {}, i, max;
        
        if(typeof attr === 'string'){
            return Backbone.Model.prototype.unset.call(this, arguments);
        }

        if(attr instanceof Array){
            for(i = 0, max = attr.length; i < max; i++){
                unset[attr[i]] = null;
            }

            return this.set(unset, _.extend({}, options, { unset: true }));
        }
    },