javascript - Change the asynchronous jQuery Dialog to be synchronous?

Question

Currently, I'm working to replace "alert'/"confirm" with the jquery dialog.

But most of legacy codes is written in some asynchronous way, which make it difficult to change. Is there any way to make jquery dialog work in a synchronous way? ( don't use loop or callback function )

   For example:
   function run()
   { 
      var result = confirm("yes or no");
      alert( result );
      \more codes here
   }

In this example the alert and other codes will be executed after user's choice.

If we use jquery dialog var result = $dialog.open() It will continue to execute the alert, which is asynchronous.

Currently, my solution is to use call back function in the OK|Cancel function. For example:

    OK: function ()
   {
       $dialog.close();
       alert("yes");
       //more codes here
    }

This method works but it is difficult to make all the synchronous codes become asynchronous, which requires a lot of change (see the following example). So I'm looking for the synchronous jQuery Dialog, is it possible??

For example: ( The real codes are much more complicated than the following example)

     function f1()
    {
          if ( confirm("hello") )    f2();
          alert("no");
    } 

    function f2()
    {
          if( confirm("world") )    f3();
          alert("no");
    }

    function f3()
    {
          return confirm("!") ;
    }

---

Another example:

vendorObject.on('some-event', function() {
    if(confirm("Do you really want to do that?")) {
        return true;
    }
    else {
        return false; // cancel the event
    }
});

... here the vendor object fires an event, which has to be cancelled if the user confirms. The event can only be cancelled if the event handler returns false - synchronously.

Answer 1

The short answer is no, you won't be able to keep your code synchronous. Here's why:

• In order for this to be synchronous, the currently executing script would have to wait for the user to provide input, and then continue.
• While there is a currently executing script, the user is unable to interact with the UI. In fact, the UI doesn't even update until after the script is done executing.
• If the script can't continue until the user provides input, and the user can't provide input until the script is finished, the closest you'll ever get is a hung browser.

To illustrate this behavior, debug your code and set a break point on the line following a line that changes the UI:

$("body").css("backgroundColor", "red");
var x = 1;  // break on this line

Notice that your page background is not yet red. It won't change to red until you resume execution and the script finishes executing. You are also unable to click any links in your page while you've got script execution paused with your debugger.

There is an exception to this rule for alert() and confirm(). These are browser controls, and are treated differently than actual web page UI elements.

The good news is that it really shouldn't be very hard to convert your code. Presumably, your code currently looks something like this:

if (confirm("continue?")) {
    // several lines of code if yes
}
else {
    // several lines of code if no
}
// several lines of code finally 

Your asynchronous version could create a function ifConfirm(text, yesFn, noFn, finallyFn) and your code would look very much the same:

ifConfirm("continue?", function () {
    // several lines of code if yes
},
function () {
    // several lines of code if no
},
function () {
    // several lines of code finally 
});

Edit: In response to the additional example you added to your question, unfortunately that code will need to be refactored. It is simply not possible to have synchronous custom confirmation dialogs. To use a custom confirmation dialog in the scenario where an event needs to either continue or cancel, you'll just have to always cancel the event and mimic the event in the yesFn callback.

For example, a link:

$("a[href]").click(function (e) {
    e.preventDefault();
    var link = this.href;
    ifConfirm("Are you sure you want to leave this awesome page?", function () {
        location.href = link;
    });
});

Or, a form:

$("form").submit(function (e) {
    e.preventDefault();
    var form = this;
    ifConfirm("Are you sure you're ready to submit this form?", function () {
        form.submit();
    });
});