src/column.js
function () {
    var sortValue = this.get("sortValue");
    if (_.isString(sortValue)) return this[sortValue];
    else if (_.isFunction(sortValue)) return sortValue;

    return function (model, colName) {
      return model.get(colName);
    };
  }
function () {
    var sortValue = this.get("sortValue");
    if (_.isString(sortValue)) return this[sortValue];
    else if (_.isFunction(sortValue)) return sortValue;

    return function (model, colName) {
      return model.get(colName);
    };
  }
function ( ) { var sortValue = this . get ( "sortValue" ) ; if ( _ . isString ( sortValue ) ) return this [ sortValue ] ; else if ( _ . isFunction ( sortValue ) ) return sortValue ; return function ( model , colName ) { return model . get ( colName ) ; } ; }
Returns an appropriate value extraction function from a model for sorting.

If the column model contains an attribute `sortValue`, if it is a string, a
method from the column instance identifified by the `sortValue` string is
returned. If it is a function, it it returned as is. If `sortValue` isn't
found from the column model's attributes, a default value extraction
function is returned which will compare according to the natural order of
the value's type.

@return {function(Backbone.Model, string): *}
Returns an appropriate value extraction function from a model for sorting .