no-this-before-super

In the constructor of a class that extends another class, this doesn't exist until super() has returned. Using this or super.method() before that throws a ReferenceError when the object is created.

The rule follows the constructor's branches, so super() must be called on every path that leads to the this. Classes without extends aren't checked.

This rule is on by default in JavaScript files. It's off in TypeScript files, where TypeScript reports the same mistake.

Configure

On by default as an error. To turn it off:

[lint.rules]
"no-this-before-super" = "off" # or "warn"

Examples

Reported:

class Admin extends User {
  constructor(name) {
    this.role = "admin";
    super.validate(name);
    super(name);
  }
}

class Admin extends User {
  constructor(name) {
    if (name) {
      super(name);
    }
    this.role = "admin";
  }
}

Not reported:

class Admin extends User {
  constructor(name) {
    super(name);
    this.role = "admin";
  }
}

class Admin extends User {
  constructor(name) {
    if (name) {
      super(name);
    } else {
      super("admin");
    }
    this.role = "admin";
  }
}