dianping/cat · error · Error

{formatterName} must be a string, function, or falsy value

Error message

{formatterName} must be a string, function, or falsy value

What it means

Error "{formatterName} must be a string, function, or falsy value" thrown in dianping/cat.

Source

Thrown at cat-home/src/main/webapp/assets/js/uncompressed/select2.js:557

                });
                query.callback(filtered);
            }
        };
    }

    /**
     * Checks if the formatter function should be used.
     *
     * Throws an error if it is not a function. Returns true if it should be used,
     * false if no formatting should be performed.
     *
     * @param formatter
     */
    function checkFormatter(formatter, formatterName) {
        if ($.isFunction(formatter)) return true;
        if (!formatter) return false;
        if (typeof(formatter) === 'string') return true;
        throw new Error(formatterName +" must be a string, function, or falsy value");
    }

  /**
   * Returns a given value
   * If given a function, returns its output
   *
   * @param val string|function
   * @param context value of "this" to be passed to function
   * @returns {*}
   */
    function evaluate(val, context) {
        if ($.isFunction(val)) {
            var args = Array.prototype.slice.call(arguments, 2);
            return val.apply(context, args);
        }
        return val;
    }

View on GitHub (pinned to e815e74d4c)

Solutions

1. Pass a string template, a formatter function, or omit the formatter option entirely.
2. Check the formatSelection/formatResult option value for an invalid type.

When it happens

Trigger: Triggered when a Select2 formatter option (formatResult, formatSelection, etc.) is given a value that is neither a string, a function, nor falsy - e.g. a number or object.

Common situations: See trigger scenarios.

AI-assisted analysis of dianping/cat@e815e74d4c (2026-08-14). Data as JSON: /api/errors/ff11842eb7838bb6. Report an issue: GitHub.