Parsing base64 content causes maximum call stack size exceeded error

Is it an issue related to Adaptive Cards?

No

Is this an accessibility issue?

No

What version of Web Chat are you using?

Unrelated

Which distribution are you using Web Chat from?

Bundle (webchat.js)

Which hosting environment does this issue primarily affect?

Web apps

Which browsers and platforms do the issue happened?

No response

Which area does this issue affect?

Attachment: Other rich cards

What is the public URL for the website?

No response

Please describe the bug

D365 conversation control hosts up to 10 webchat control instances at the same time.
When rendering multiple large attachments on multiple webchat control instances at the same time. the error below could be generated intermittently.

The error is thrown at the function:
https://ersuolocaldev.blob.core.windows.net/share/regex_parse_error.png
 
"stack":"RangeError: Maximum call stack size exceeded\n at RegExp.exec ()\n at u (https://oc-cdn-public-eur.azureedge.net/convcontrol/lib/webchat.js:2:2300840)\n/n) at t.default (https://oc-cdn-public-eur.azureedge.net/convcontrol/lib/webchat.js:2:2299659)\n/n) at u (https://oc-cdn-public-eur.azureedge.net/convcontrol/lib/webchat.js:2:1946002)\n/n) at Xi (https://oc-cdn-public-eur.azureedge.net/convcontrol/Scripts/vendors.js?ver=3281cde91656f30c4a62:2:4489600)\n at xa (https://oc-cdn-public-eur.azureedge.net/convcontrol/Scripts/vendors.js?ver=3281cde91656f30c4a62:2:4535646)\n at wl (https://oc-cdn-public-eur.azureedge.net/convcontrol/Scripts/vendors.js?ver=3281cde91656f30c4a62:2:4528406)\n at Sl (https://oc-cdn-public-eur.azureedge.net/convcontrol/Scripts/vendors.js?ver=3281cde91656f30c4a62:2:4528331)\n at fl (https://oc-cdn-public-eur.azureedge.net/convcontrol/Scripts/vendors.js?ver=3281cde91656f30c4a62:2:4525354)\n at https://oc-cdn-public-eur.azureedge.net/convcontrol/Scripts/vendors.js?ver=3281cde91656f30c4a62:2:4477009","message":"Maximum call stack size exceeded"},

Do you see any errors in console log?

"stack":"RangeError: Maximum call stack size exceeded\n    at RegExp.exec (<anonymous>)\n    at u (https://oc-cdn-public-eur.azureedge.net/convcontrol/lib/webchat.js:2:2300840)\n    at t.default (https://oc-cdn-public-eur.azureedge.net/convcontrol/lib/webchat.js:2:2299659)\n    at u (https://oc-cdn-public-eur.azureedge.net/convcontrol/lib/webchat.js:2:1946002)\n    at Xi (https://oc-cdn-public-eur.azureedge.net/convcontrol/Scripts/vendors.js?ver=3281cde91656f30c4a62:2:4489600)\n    at xa (https://oc-cdn-public-eur.azureedge.net/convcontrol/Scripts/vendors.js?ver=3281cde91656f30c4a62:2:4535646)\n    at wl (https://oc-cdn-public-eur.azureedge.net/convcontrol/Scripts/vendors.js?ver=3281cde91656f30c4a62:2:4528406)\n    at Sl (https://oc-cdn-public-eur.azureedge.net/convcontrol/Scripts/vendors.js?ver=3281cde91656f30c4a62:2:4528331)\n    at fl (https://oc-cdn-public-eur.azureedge.net/convcontrol/Scripts/vendors.js?ver=3281cde91656f30c4a62:2:4525354)\n    at https://oc-cdn-public-eur.azureedge.net/convcontrol/Scripts/vendors.js?ver=3281cde91656f30c4a62:2:4477009","message":"Maximum call stack size exceeded"},

How to reproduce the issue?

1. open multiple webchat control instances and attempted to render large attachments
2. quickly refresh the components
3. intermittently the rendering error could happen. The memory limitation seems also play a role there.

What do you expect?

From D365 OC conversation control, previously, we may directly pass the base64 content to webchat control to render at this logic had not been changed for years. Starting Oct, multiple VIP customers started report the rendering issue of the attachments. The fix we were providing is always convert the base64 content to blob before sending to webchat control.
No immediate mitigation needed from webchat control now.

What actually happened?

The regex expression execution seems used a lot of computing power when parsing the large attachments simultaneously. When the error mentioned above happens, the browser become lagging and nonresponsive.

Do you have any screenshots or recordings to repro the issue?

https://ersuolocaldev.blob.core.windows.net/share/regex_parse_error.png

Adaptive Card JSON

No response

Additional context

No response

Start by reproducing the issue with multiple Web Chat control instances rendering large base64 attachments, following the listed refresh steps and observing webchat.js and vendors.js. Investigate the attachment-rendering path associated with the reported RegExp.exec stack trace; done means large simultaneous attachments render without a call-stack overflow or an unresponsive browser.