I have a bit of JavaScript code that is specified in a configuration file on the server-side. Since I can't specify a JavaScript function in the configuration language (Lua), I have it as a string. The server returns the string in some JSON and I have the client interpret it using a clean-up function:

parse_fields = function(fields) {

    for (var i = 0; i < fields.length; ++i) {

        if (fields[i].sortType) {

            sort_string = fields[i].sortType;

            fields[i].sortType = eval(sort_string);

        }

        return fields;

    }

}; 

So basically it just evaluates sortType if it exists. The problem is that Firebug is reporting a Syntax error on the eval() line. When I run the same steps on the Firebug console, it works with no problems and I can execute the function as I expect. I've tried some different variations: window.eval instead of plain eval, storing the sortType as I've done above, and trying small variations to the string.

A sample value of fields[i].sortType is function(value) { return Math.abs(value); }. Here's the testing I did in Firebug console:

>>> sort_string

function(value) { return Math.abs(value); }

>>> eval(sort_string)

function()

>>> eval(sort_string)(-1)

1

and the error itself in Firebug:

syntax error

[Break on this error] function(value) { return Math.abs(value); }

The last bit that may be relevant is that this is all wrapped in an Ext JS onReady() function, with an Ext.ns namespace change at the top. But I assumed the window.eval would call the global eval, regardless of any possible eval in more specific namespaces.

Any ideas are appreciated.