no-public-instance-class-fields.md

no-public-instance-class-fields

This prevents the use of Instance Public Class Fields

class Foo {
  bar = 1
}

These will not be allowed because they are not supported in the following browsers:

• Edge < 79
• Safari < 16.0
• Firefox < 69
• Chrome < 72

What is the Fix?

You can move these assignments to within the class constructor function, using either Object.defineProperty (or a simple assignment) to add instance properties:

class Foo {
  constructor() {
    Object.defineProperty(this, 'bar', { configurable: true, enumerable: true, writable: true, value: 1 })
  }
}

class Foo {
  constructor() {
    this.bar = 1
  }
}

This can be safely disabled if you intend to compile code with the @babel/plugin-transform-class-properties Babel plugin, or @babel/preset-env.