Question

Okay I am working with some jquery creating dynamic popups. However, periodically the response will be the name of a function that I need to call instead of actual data and I am trying to figure out how to do this..

success: function(response) {
                                var obj = $.parseJSON(response);
                                if (obj.response == 'false') {
                                    $('#popuperrDisplay').html(obj.msg);
                                    $('#popuperrors').show();
                                } else {
                                    if (obj.response == 'redirect') {
                                        window.location.href = obj.msg; 
                                    } else if (obj.response == 'function') {
                                        call obj
                                    } else {
                                        $(this).dialog('close');
                                    }
                                }
                            }

This is the current portion of my jquery. I need to figure out how I can send the name of a JS function through json_encode and have JS actually call that function

Answer 1

If the function is defined globally (on the window object), you could simply invoke it like so:

if (obj.response === 'function' &&            // 1
    typeof window[obj.msg] !== 'undefined') { // 2

    window[obj.msg]();                        // 3
    // or...
    window[obj.msg].apply(null, obj.args);    // 4
}

1. checks whether the type of the response is a function.
2. checks if there is a function with the given name defined on the window object.
3. calls that function.
4. calls that function and provides it with an array of arguments.

Edit: (window[] syntax)

To further clarify, window['showPopup'] accesses the showPopup member of the window object. It’s the same as doing window.showPopup. Only, the [] syntax has the advantage of receiving a string instead of actual code.

window['showPopup'] will return an object (if defined); let it be a function for our particular example.

We then call that function object by using the () operator, like so: window['showPopup'](). Once again, this is the same as doing this: window.showPopup().

Edit 2: (invoke with arguments)

If the function has to be invoked with an array of arguments, we can use apply. Invoking the function would then look like:

window['showPopup'].apply(null, arrayOfArgs);

Where arrayOfArgs is an array containing the arguments.