Function printFunctionParameters

src/language-js/print/function-parameters.js:65–196

(
  path,
  options,
  print,
  shouldExpandParameters,
  shouldPrintTypeParameters,
)

- `ComponentTypeAnnotation` (Flow)
*/
function printFunctionParameters(
  path,
  options,
  print,
  shouldExpandParameters,
  shouldPrintTypeParameters,
) {
  const functionNode = path.node;
  const parameters = getFunctionParameters(functionNode);
  const typeParametersDoc =
    shouldPrintTypeParameters && functionNode.typeParameters
      ? print("typeParameters")
      : "";

  if (parameters.length === 0) {
    return [
      typeParametersDoc,
      "(",
      printDanglingCommentsInList(
        path,
        options,
        functionParameterDanglingCommentFilter,
      ),
      ")",
    ];
  }

  const { parent } = path;
  const isParametersInTestCall = isTestCall(parent);
  const shouldHugParameters = shouldHugTheOnlyFunctionParameter(functionNode);
  const printed = [];
  iterateFunctionParametersPath(path, (parameterPath, index) => {
    const isLastParameter = index === parameters.length - 1;
    if (isLastParameter && functionNode.rest) {
      printed.push("...");
    }
    printed.push(print());
    if (isLastParameter) {
      return;
    }
    printed.push(",");
    if (isParametersInTestCall || shouldHugParameters) {
      printed.push(" ");
    } else if (isNextLineEmpty(parameters[index], options)) {
      printed.push(hardline, hardline);
    } else {
      printed.push(line);
    }
  });

  // If the parent is a call with the first/last argument expansion and this is the
  // params of the first/last argument, we don't want the arguments to break and instead
  // want the whole expression to be on a new line.
  //
  // Good:                 Bad:
  //   verylongcall(         verylongcall((
  //     (a, b) => {           a,
  //     }                     b,