Let's unravel this JavaScript enigma: the code snippet window.confirm = divConfirm(strMessage) awaits

Question

Let's unravel this JavaScript enigma: the code snippet window.confirm = divConfirm(strMessage) awaits

Imagine a scenario where you have an old website with a lot of existing JS code. If a user wants to update all the alert messages to modern, stylish Div-based alerts commonly used in jQuery, YUI, Prototype, etc., there are primarily three types of JS dialogs to consider:

1. alert

To change this, it's simple: just create a new function that displays the div popup and message, then override the window.alert function.


function showDivAlert(strMessage){ <br/>
//div popup logic and code <br/>
} <br/>
 <br/>
window.alert = showDivAlert; <br/>

2. prompt

This one is also straightforward - write a function that accepts a string and displays a text box for input value. Since the return action is based on clicking the "OK" button, the process is easy.


function showDivPrompt(strMessage){ <br/>
//div pop up to show the text box and accept input from the user <br/>
} <br/>
window.prompt = showDivPrompt; <br/>

3. confirm

Unlike the first two, overriding and modifying the default confirm dialog has its complications. The default JS confirm dialog halts JS execution until the user clicks OK or Cancel, which determines the return value (true/false). However, using a div popup does not stop the execution flow, posing a problem. Implementation of the confirm dialog is possible by binding methods for both OK and CANCEL actions to their respective buttons. This results in a function signature like:

function customConfirm(msg, OkAction(), CancelAction)

Unfortunately, this solution does not facilitate a site-wide change of the confirm dialog as easily as with the alert dialog. Question
While I'm unsure if achieving this is possible, it seems feasible using certain JS patterns. Please let me know if such an approach is viable.

asp.net javascript jquery ajax

Answer 1

Answer №1

It seems that changing the confirm dialog across the site is a problem without an easy solution like we did with alert();

That's right. Replicating the synchronous behavior of alert/confirm/prompt functions in native JavaScript is not feasible. Although there is a non-standard method called showModalDialog that can achieve this using a separate pop-up document, it's not well-supported by all browsers and is generally discouraged.

Therefore, the plugin-replacement approach will not work here. You'll need to manually update every instance where these methods are used in your script.

The common practice is to use inline anonymous functions to maintain local variables through closures. For example, you can replace:

function buttonclick() {
    var id = this.id;
    if (confirm('Are you sure you want to frob ' + id + '?'))
        frob(id);
    wipe(id);
}

with:

function buttonclick() {
    var id = this.id;
    myConfirm('Are you sure you want to frob ' + id + '?', function(confirmed) {
        if (confirmed)
            frob(id);
        wipe(id);
    });
}

If you require preservation of the this keyword, you may need to use nested closures or function.bind. Handling calls to confirm within a loop adds complexity to the situation.

Additionally, it's crucial to ensure that critical global state remains unchanged while the confirm box is active. One way to mitigate this risk is by overlaying a page element to prevent user interactions during the confirmation process. However, timeouts can still pose challenges in this scenario.

Answer 2

It seems that changing the confirm dialog across the site is a problem without an easy solution like we did with alert();

That's right. Replicating the synchronous behavior of alert/confirm/prompt functions in native JavaScript is not feasible. Although there is a non-standard method called showModalDialog that can achieve this using a separate pop-up document, it's not well-supported by all browsers and is generally discouraged.

Therefore, the plugin-replacement approach will not work here. You'll need to manually update every instance where these methods are used in your script.

The common practice is to use inline anonymous functions to maintain local variables through closures. For example, you can replace:

function buttonclick() {
    var id = this.id;
    if (confirm('Are you sure you want to frob ' + id + '?'))
        frob(id);
    wipe(id);
}

with:

function buttonclick() {
    var id = this.id;
    myConfirm('Are you sure you want to frob ' + id + '?', function(confirmed) {
        if (confirmed)
            frob(id);
        wipe(id);
    });
}

If you require preservation of the this keyword, you may need to use nested closures or function.bind. Handling calls to confirm within a loop adds complexity to the situation.

Additionally, it's crucial to ensure that critical global state remains unchanged while the confirm box is active. One way to mitigate this risk is by overlaying a page element to prevent user interactions during the confirmation process. However, timeouts can still pose challenges in this scenario.

Answer 3

Answer №2

Each of the 3 methods mentioned above actually halts javascript execution, not just the confirm dialog, because they all create modal dialogs. Personally, I prefer to keep things as asynchronous as possible since modal dialogs block interaction with the current document.

Your best option would be to utilize callback functions from the new confirm popup, as you had suggested.

I'm a bit unclear on what your exact goal is here. It seems like you want to:

Execute some javascript code
Show a "confirm" box
Pause until the user clicks either the ok or cancel button
Resume code execution upon clicking ok, and return if the user clicks cancel.

The reason for doing this is that replacing the function with callbacks would necessitate rewriting every section of code that uses the confirm function. In my opinion, it would be better to restructure the code so it runs asynchronously. There's no way to delay script execution without freezing up the document, which includes the actions of your dialog prompts.

Answer 4

Each of the 3 methods mentioned above actually halts javascript execution, not just the confirm dialog, because they all create modal dialogs. Personally, I prefer to keep things as asynchronous as possible since modal dialogs block interaction with the current document.

Your best option would be to utilize callback functions from the new confirm popup, as you had suggested.

I'm a bit unclear on what your exact goal is here. It seems like you want to:

Execute some javascript code
Show a "confirm" box
Pause until the user clicks either the ok or cancel button
Resume code execution upon clicking ok, and return if the user clicks cancel.

The reason for doing this is that replacing the function with callbacks would necessitate rewriting every section of code that uses the confirm function. In my opinion, it would be better to restructure the code so it runs asynchronously. There's no way to delay script execution without freezing up the document, which includes the actions of your dialog prompts.

Answer 5

Answer №3

By switching the roles of Alert / Prompt / Confirm, you can introduce delays in code execution to accommodate user interactions.

Once these functions are overridden, the code can seamlessly continue its operation.

To implement this, adjustments need to be made throughout the code to emulate asynchronous behavior.

After making these changes, various plugins like sexy-alert-box can be utilized to replace standard Alert / Prompt / Confirm functionalities.

Answer 6

By switching the roles of Alert / Prompt / Confirm, you can introduce delays in code execution to accommodate user interactions.

Once these functions are overridden, the code can seamlessly continue its operation.

To implement this, adjustments need to be made throughout the code to emulate asynchronous behavior.

After making these changes, various plugins like sexy-alert-box can be utilized to replace standard Alert / Prompt / Confirm functionalities.

Answer 7

Answer №4

To create a confirm function, the signature would look like this:

 function customConfirm(message, onOK, onCancel);

Usage example:

 function customConfirm(message, onOK, onCancel){
   var userResponse = promptUserForConfirmation();
   if (userReponse) {
     onOK();
   } else {
     onCancel();
   }
 }

In order to pass functions as arguments to another function, simply provide the function name without parentheses. The function structure remains the same.

Answer 8

To create a confirm function, the signature would look like this:

 function customConfirm(message, onOK, onCancel);

Usage example:

 function customConfirm(message, onOK, onCancel){
   var userResponse = promptUserForConfirmation();
   if (userReponse) {
     onOK();
   } else {
     onCancel();
   }
 }

In order to pass functions as arguments to another function, simply provide the function name without parentheses. The function structure remains the same.

Let's unravel this JavaScript enigma: the code snippet window.confirm = divConfirm(strMessage) awaits

Answer №1

Answer №2

Answer №3

Answer №4

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