Removal of the showModalDialog API

Question

With the impending removal of the showModalDialog API from various browsers, our company like many others who provide large scale enterprise web applications are now faced with a significant dilemma.

Whilst we have centralised the calls to showModalDialog down to 3 lines of code, we extensively rely on this code to provide feedback from modal user prompts (a quick search of the solution reveals around 2400 instances).

We could rip out showModalDialog fairly easily and replace it with a Javascript/css based alternative, that's not a problem. The issue we face is that all of the calling code will no longer be blocking e.g.

if(doConfirm(...)) {
   ...
} else {
   ...
} 

The above will simply fall through due to the introduction of a non-blocking alternative. We also cannot use the in-built blocking methods (alert, confirm) as the dialog buttons are customised in many cases and are also styled to fit in with our application.

Based on the above, are there any pragmatic workarounds/solutions that could be employed to avoid having to re-factor so much legacy previously blocking code?

Answer 1

You won't get around using asynchronous, event-based code.

pragmatic workarounds to avoid having to re-factor the code manually?

You can try a javascript-to-javascript compiler that brings the await keyword to js. It should automatically transpile your code to an asynchronous version.

_{Disclaimer: I haven't used any of these}

Answer 2

You can avoid using callback functions by using my showModalDialog polyfill, which pauses execution of subsequent statements until the modal is closed. It does so by using generators, promises and the yield keyword. It works in the newest Opera and Google Chrome.

Answer 3

In jQuery's 1.11.4 version, there is a built-in <dialog> you can use, which also allows for capturing a callback parameter on close.

    $("#dialog").dialog({
        autoOpen: false,
        width: 500,
        height: 500,
        modal: true
        buttons: [
            {
                text: "Ok",
                click: function () {
                    $(this).dialog("close");
                }
            },
            {
                text: "Cancel",
                click: function () {
                    $(this).dialog("close");
                }
            }
        ]
    });

Your value could be captured in the callback functions from the button click events.

You could even add HTML to append your own 'x' button to the existing "Close" button and hide the original, so you could do whatever you wanted:

    $(document).ready(function () {
        var closeHtml = '<a href="#" id="dialog-close" style="position: absolute; top: 0; right: 4px; font-size: 20px; color: #000; text-decoration: none; outline: none;">&times;</a>';
        $("button[title='Close']").css('display', 'none').parent().append(closeHtml);

    });

then attach a click event to the dialog-close ID from the 'x' button:

    var url = 'https://www.cnn.com';

    // Link to open the dialog
    $("#dialog-link").click(function (event) {
        var dialog = $("#dialog");
        dialog.dialog("open");

        dialog.html('<iframe id="dialog-body" scrolling="yes" src="' + url + '" style="border: 0; width: 100%; height: 100%;"></iframe>');

        $("#dialog-close").on('click', function (e) {
            // ...do whatever you want here, then...
            $("button[title='Close']").click();
            //e.preventDefault();
            //dialog.close();
        });

        event.preventDefault();
    });

Only caveat, since this uses IFrame, it might not work if the security on the site prevents bringing in external sites to your own site, if you are using it in this way. Google, for example, prevents this use with their site.

This should be a cross-platform example - I've tested it in IE 11. "Polyfill", that I've seen others say is another way to do this, is NOT, and does NOT work in IE because it relies on Promise, which is not supported in IE, as it shows at the bottom of this page: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise