quick-lint-js

Find bugs in JavaScript programs.

E0151: invalid function parameter

A function parameter can be a variable name, an array destructuring, or an object destructuring. It is a syntax error for a function parameter to look like a function call or any other expression:

const join = (string, delimiter += ",") =>
  string.join(delimiter);

function cssClass(classes()) {
  return join(Object.keys(classes), " ");
}

To fix this error, write = to make a parameter have a default value:

const join = (string, delimiter = ",") =>
  string.join(delimiter);

Alternatively, remove the parentheses indicating a function call:

function cssClass(classes) {
  return join(Object.keys(classes), " ");
}

Documentation for other errors