# E0303: 'this' must be the first parameter

TypeScript allows you to explicitly declare the `this` parameter. It is a syntax error to write another parameter before the `this` parameter:

    $("form button").each(function (
      index: number,
      this: Element,
    ) {
      console.log(`disabling button #${index}`);
      $(this).disable();
    });

To fix this error, move `this` to the start of the parameter list:

    $("form button").each(function (
      this: Element,
      index: number,
    ) {
      console.log(`disabling button #${index}`);
      $(this).disable();
    });

Introduced in quick-lint-js version 2.10.0.

Documentation for other errors