IE11中swal().then()回调无法触发的技术求助

Hey there, let's break down why your SweetAlert2's .then() isn't firing in IE11 and walk through actionable checks to fix it:

1. Verify the ES6 Promise Polyfill is Actually Working #

You're loading es6-promise@3.2.1, but many older promise polyfills require an explicit initialization call to attach to the global scope in IE11. Add this line right after the script tag for es6-promise:

<script src="https://npmcdn.com/es6-promise@3.2.1"></script>
<script>ES6Promise.polyfill();</script>

Without this, the Promise object might not be available globally when SweetAlert2 loads, so its promise-based API won't function as expected.

Also, confirm the polyfill is loading at all:

• Open IE11's F12 DevTools > Network tab
• Refresh the page and check if es6-promise@3.2.1 appears with a 200 status
• If it's missing, your server-side Request.Browser check might not detect IE11 correctly. IE11's user agent string can be tricky—try updating the condition to include checks for Trident, or switch to a client-side check like if (typeof Promise === 'undefined') to load the polyfill only when needed.

2. Validate SweetAlert2's IE11 Compatibility #

Your current setup uses the standard SweetAlert2 build, but ensure you're on a version that explicitly supports IE11. Older versions might have broken promise handling in legacy browsers. Also, double-check that the IE9-specific script isn't accidentally loading in IE11—your conditional comment <!--[if IE 9]> should prevent this, but it's worth confirming in the Network tab.

For testing, try using the sweetalert2-ie9 build for IE11 (remove the standard SweetAlert2 script first to avoid conflicts):

<!--[if lte IE 11]>
<script src="~/bower_components/sweetalert2-ie9/dist/sweetalert2.min.js"></script>
<![endif]-->

3. Fall Back to SweetAlert2's Callback Syntax #

Older SweetAlert2 versions had better support for traditional callbacks in IE11 than promise chaining. Rewrite your code to use the callback parameter instead of .then():

swal({
    title: translations.AreYouSureYouWantToSubmit,
    text: '',
    type: 'warning',
    showCancelButton: true,
    confirmButtonText: '<i class="fas fa-thumbs-up"></i> ' + globalTranslations.Yes,
    cancelButtonText: '<i class="fas fa-thumbs-down"></i> ' + globalTranslations.No,
    confirmButtonClass: 'btn btn-success',
    cancelButtonClass: 'btn btn-danger',
    buttonsStyling: false
}, function(isConfirmed) {
    if (isConfirmed) {
        // Your original .then() logic goes here
        vm.state($(event.currentTarget).data('state'));
        // ... rest of your validation and submission code
    }
});

This bypasses promise-related issues entirely and is a reliable fallback for IE11.

4. Check for Silent Errors in IE11 DevTools #

IE11's console might hide errors that break the promise chain. Open F12 DevTools > Console tab, enable "Errors" filtering, and refresh the page. Look for:

• "Promise is undefined" (confirms the polyfill isn't working)
• Script errors from SweetAlert2 itself
• Silently failing validation logic that stops execution before .then() triggers

5. Ensure No Scripts Overwrite the Global Promise Object #

Some third-party scripts might overwrite the global Promise in IE11. In DevTools > Console, run typeof Promise—it should return "function". If it returns "undefined" or another value, another script is interfering with your polyfill.

内容的提问来源于stack exchange，提问作者Glitch_Doctor