Example of how NOT to build a JavaScript class.

js-class-footgun.md

JS class footgun

I came across some code awhile ago that, though I can't share exactly, I wanted to document as a "footgun."

You should never have a class that can be used both as a singleton with helper methods and can be instantiated.

Even if you did, there should never be static and public methods — by the same name — that do different things.

/*
  This is a pseudo coded version of
  a bad JavaScript `class` I noticed.

  I thought it'd be funny to document.
*/

class Robot {
  // Available directly.
  static helpHumans() {
    console.log('I help humans!');
  }

  // Available via `new`.
  helpHumans() {
    console.log('I kill humans!');
  }
}

const myRobot1 = Robot;
const myRobot2 = new Robot();

// Logs: "I help humans!"
console.log(
  myRobot1.helpHumans()
);

// Logs: "I kill humans!"
console.log(
  myRobot2.helpHumans()
);