We have a lightning component that was working fine previously in IE11, but as we change our component attribute from aura to the lightning component like below:

<lightning:buttonMenu aura:id="menu" onselect="{! c.handleSelect }" alternativeText="Show menu"> etc. 

After this change our component not working in IE11 and through the JS exception. enter image description here

Our component starting giving the following JS Exception in IE11.

Failure when getting component class definition [Expected ';']

This error only comes in IE11.

The component works fine in all other major supported browsers like chrome, safari, firefox, edge.

  • You changed it from what?
    – glls
    Nov 27, 2019 at 0:23
  • Our Component was working perfectly in IE11 before we change the aura component to the lightning component in our new release as we know that the Aura component will not be supported in API 47. One of the output method we change in the component is <ui:outputDate value="{!v.myDate}"/> to <lightning:formattedDateTime value="1479944705000" year="2-digit" month="short" day="2-digit" weekday="long"/> like this, we have changed many other UI tags with lightning
    – Faisal
    Nov 27, 2019 at 13:07

1 Answer 1


I have resolved the issue. Solution: Internet Explorer 11 does not support let in for/for-in loop iteration scope. I have changed the let with var in my JS Controller and loop through for loop indexing and it works fine.

reference: https://stackoverflow.com/questions/54989779/internet-explorer-11-javascript-let-statement

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