Question

Original code from JamieMThomas, a (really good guy who is trying to combine Microsoft JQuery Templates and Linking) :

mapping[binding.field] = {
    convert: function (value, source, target) {
        if (binding.converter && binding.converter.convert) {
            value = binding.converter.convert(value, source, target)
                if (value === undefined)
                    return;
        }
        $(target).attr(attrName, value);
    }
};

I am trying to hack it to allow binding.field to work with a string like "LPC[0].itemid" (literally a string). I am using eval as a terrible choice, but it’s the fastest thing I can do (and will rewrite it later). I originally tried assigning the content to the eval(”) itself, but it didn’t allow me.

eval('(mapping.' + binding.field + ')') =
    { // rest is the same
    convert: function (value, source, target) {
        if (binding.converter && binding.converter.convert) {
            value = binding.converter.convert(value, source, target)
                if (value === undefined)
                    return;
        }
        $(target).attr(attrName, value);
    }
};

Obviously an invalid assignment on the left hand side. How could I accomplish this?

Answer 1

You can put the entire assignment in the eval:

eval('mapping.' + binding.field + ' = { ... }');

This would be a very large string containing the function definition
To make the string smaller, you can put the function in an external variable:

var converter = function (value, source, target) {
    if (binding.converter && binding.converter.convert) {
        value = binding.converter.convert(value, source, target)
            if (value === undefined)
                return;
    }
    $(target).attr(attrName, value);
};
eval('mapping.' + binding.field + ' = { convert: converter }');