ES6 introduced classes to JavaScript, but they can be too simplistic for complex applications. Class fields (also referred to as class properties) aim to deliver simpler constructors with private and static members. The proposal is currently a TC39 stage 3: candidate and is likely to be added to ES2019 (ES10). Private fields are currently supported in Node.js 12, Chrome 74, and Babel. A quick recap of ES6 classes is useful before we look at how class fields are implemented. ES6…