I am working on an EOS dApp that is listing dogs (it could be other items) and displaying them on an HTML page. The dApp has a function in its JS file to add dogs.

This dApp is working with nodeos up and running, a Python server up and running, and Scatter.

In my HTML page, although I can see some elements such as the textbox and the button to add dogs, the list of dogs is not diplayed. It should come inside my <ul id="doglist"></>

Instead, I am getting an error in my console:

Uncaught (in promise) SyntaxError: Unexpected token < in JSON at position 0


My asyncToGenerator.js file reads as follows:

function asyncGeneratorStep(gen, resolve, reject, _next, _throw, key, arg) {
  try {
    var info = gen[key](arg);
    var value = info.value;
  } catch (error) {

  if (info.done) {
  } else {
    Promise.resolve(value).then(_next, _throw);

function _asyncToGenerator(fn) {
  return function () {
    var self = this,
        args = arguments;
    return new Promise(function (resolve, reject) {
      var gen = fn.apply(self, args);

      function _next(value) {
        asyncGeneratorStep(gen, resolve, reject, _next, _throw, "next", value);

      function _throw(err) {
        asyncGeneratorStep(gen, resolve, reject, _next, _throw, "throw", err);


module.exports = _asyncToGenerator;

It seems the reject(error); line in the first function is causing an issue.

If you need to see my main.js file that is part of my front end, I can post it here.

Thank you for your assistance!

1 Answer 1


TLDR That unexpected token < is a strong clue that the response was HTML instead of JSON. While you expected to get JSON

  • Yes, it should be the issue or part of the issue, but what do I need to do to correct my code to make it work? If you need me to paste my main.js code here for clarification, please let me know and I will do it.
    – vinchik
    Oct 4, 2020 at 10:35

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