IE11 - Component does not load when class attribute is used in JSX template

[nmina]

Stencil version:

 @stencil/core@1.1.8

I'm submitting a:
[x] bug report
[ ] feature request
[ ] support request => Please do not submit support requests here, use one of these channels: https://stencil-worldwide.herokuapp.com/ or https://forum.ionicframework.com/

Current behavior:
Web Component does not load in IE11 with @stencil/core versions 1.1.8 and above when class attribute is used in JSX template.

Expected behavior:
Component should load in IE11.

Steps to reproduce:
Create a Stencil starter project using the CLI.

npm init stencil
Pick a starter > component
Project name > any-name

in my-component.tsx, add class attribute in the div tag:

import {Component, Prop, h, Element} from '@stencil/core';
import {format} from '../../utils/utils';

@Component({
  tag: 'my-component',
  styleUrl: 'my-component.css',
  shadow: false
})
export class MyComponent {
  /**
   * The first name
   */
  @Prop() first: string;
  
  /**
   * The middle name
   */
  @Prop() middle: string;
  
  /**
   * The last name
   */
  @Prop() last: string;
  
  @Element() el: HTMLElement;
  
  private getText(): string {
    return format(this.first, this.middle, this.last);
  }
  
  render() {
    return <div class="message">Hello, World! I'm {this.getText()}</div>;
  }
}

Add --es5 in package.json's start script:

"start": "stencil build --dev --watch --serve --es5"

then run the app in IE11.

Console shows the following error:

Related code:

[arielsalminen]

If it helps, this regression was introduced in "@stencil/core": "1.1.8" and downgrading to "@stencil/core": "1.1.7" fixes the issue.

[nmina]

Thanks @viljamis. Yes I have my application version set to 1.1.7 until this is fixed. I guess unless they decided to move forward and leave IE11 behind. lol

[cary-smith]

We are also stuck on 1.1.7 after finally getting off of 0.15.2. Woohoo! This is the only roadblock and I have submitted a pull.