max-params-function-def

Daniel StrongError ProneInformational

No tags

No CWE or CVE

This rule warns once a function has five parameters because this can be difficult to maintain.

If you need this many parameters, you might be better off combining the parameters into an object or splitting your function.

Ast Rule: function definition

max-params-function-def

How to write a rule

const MAX_PARAMS = 5;

function visit(node, filename, code) {
  if (!node.parameters) return;
  if (node.parameters?.values.length < MAX_PARAMS) return;

  const error = buildError(
    node.name.start.line,
    node.name.start.col,
    node.name.end.line,
    node.name.end.col,
    `Having this many parameters can be difficult to manage. Consider splitting this function.`,
    "INFORMATIONAL",
    "BEST_PRACTICES"
  );
  addError(error);
}

valid-number-of-params.jsx

Expected test result: no error

function a() {}
function b(foo) {}
function c(foo, bar) {}
function d(foo, bar, baz) {}
function e(foo, bar, baz, qux) {}

too-many-params.jsx

Expected test result: has error

function a(foo, bar, baz, qux, fred) {}
function b(foo, bar, baz, qux, fred, thud) {}

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