callcc

callcc.js

class ContError extends Error { returnValue = undefined; }

function callcc(fnCont) {
  const contErr = new ContError("Unable to continue current continuation.");
  const fnEscape = (returnValue) => {
    contErr.returnValue = returnValue;
    throw contErr;
  }
  try {
    return fnCont(fnEscape);
  } catch (e) {
    if (e === contErr)
      return contErr.returnValue;
    else
      throw e;
  }
}