Uglifier complains about field declaration syntax

[toomanyjoes]

I'm am using the harmony option in my Rails configuration and the latest version of the gem as of this time (4.2.0):

config.assets.js_compressor = Uglifier.new(harmony: true)

But when I try to use field declaration syntax inside a js class uglifier complains:

Uglifier::Error: Unexpected token: punc (;)

or

Uglifier::Error: Unexpected token: operator (=)

My javascript class looks like this as shown here https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes:

class Rectangle {
  width;
  height = 0;
  constructor(height, width) {    
    this.height = height;
    this.width = width;
  }
}

Is there a way to fix this? And if not is there a way to disable uglifier for specific lines or an entire file?

[ahorek]

try https://github.com/ahorek/terser-ruby