fake-error-is-error.js

// -*- coding: utf-8, tab-width: 2 -*-
// https://github.com/mk-pmb/is-error-js/issues/5

const isError = require('is-error');

const FakeError = function() {
  this[Symbol.toStringTag] = 'Error';
};


function preview(x) {
  if (!x) { return x; }
  if (!x.slice) { return x; }
  return x.slice(0, 64).concat('…');
}

function inspect(x) {
  const {
    name,
    message,
    stack,
  } = x;
  console.log({
    obj2str: Object.prototype.toString.call(x),
    isError: isError(x),
    keys: Object.keys(x),
    message,
    name,
    stack: preview(stack),
  });
}

inspect(new FakeError('fake'));
inspect(new Error('legit'));

// { obj2str: '[object Error]',
//   isError: true,
//   keys: [],
//   message: undefined,
//   name: undefined,
//   stack: undefined }
// { obj2str: '[object Error]',
//   isError: true,
//   keys: [],
//   message: 'legit',
//   name: 'Error',
//   stack: 'Error: legit\n    at Object.<anonymous> (/tmp/test.js:34:9)\n    a…' }