Tag Archives: JavaScript

Parsing Hash Args for Cognito Auth – Javascript

Hi everyone,

A quick post on a function for parsing hash args when using AWS Congito.


Just in case the fiddle ever disappears:

const parseHashArgs = aURL => {

  aURL = aURL || window.location.href;

  var vars = {};
  var hashes = aURL.slice(aURL.indexOf('#') + 1).split('&');

  for (var i = 0; i  1) {
      vars[hash[0]] = hash[1];
    } else {
      vars[hash[0]] = null;

  return vars;


Thanks to this link on Github: https://gist.github.com/miohtama/1570295/289d5a82e65663c9b515c88186a268c6dd1fddb7


NavLink ListItems not Applying activeClassName class when Clicked On – ReactJS React-Router MaterialUI

Hi everyone,

A bit of a hairy issue I ran into today that took a while to track down. I’m using React Router with Material UI to render a Drawer as a sidebar:

The issue was that some links were not applying the expected activeclass:

	<ListItemText primary={
	} />

After trawling through react-router I eventually found a post on github that mentioned a similar issue: https://github.com/ReactTraining/react-router/issues/4638

The solution turned out to be wrapping all relevant components with withrouter.

Uncaught SyntaxError: Unexpected token < – ReactJS Build

Hi everyone,

A ReactJS issue I ran into after running npm run build:

Uncaught SyntaxError: Unexpected token <

This one took a while to track down but it essentially boils down to the built index.html file referencing paths relatively:

Issue: index.html was referencing

Instead of:

This meant that anytime a page was accessed directly it attempted to load the static files from the wrong directory. To fix it, I had to update the homepage node in package.json

"version": "0.1.0",
  "homepage": "./",
  "private": true,

Instead use:
"version": "0.1.0",
  "homepage": "/",
  "private": true,

Hopefully that’s able to help someone else out, took a while to track down!

npm ERR! missing script: flow npm ERR! A complete log of this run can be found in: – ReactJS and Flow

Hi everyone,

I ran into the following error while trying to setup flow:

npm ERR! missing script: flow
npm ERR! A complete log of this run can be found in:

To fix this, just add “flow”: “flow” as a new entry under “scripts” in your package.json file.

See the following link for more info:

Error Adding Card – Assembly Payments

Hi everyone,

Just working with Assembly Payments and ran into the following error while following their documentation on Capturing a Credit Card:

errors”:{“card_account”:[“Error adding card. If error persists, please contact our support team.”]

The error is pretty vague, but it does seem that the credit card info they use in the documentation has expired. I tested with another credit card and it went through:

                    promisepay.createCardAccount(token, {

                        full_name: "Bella Buyer",
                        number: "4242424242424242",
                        expiry_month: "12",
                        expiry_year: "2021",
                        cvv: "123"
                    }, success, fail)

I was talking to support about another issue and they mentioned the following page: https://reference.assemblypayments.com/#credit-card-data

Including an Externally Hosted Script in ReactJs

Hi everyone,

Just a quick example of how to include an externally hosted js file in a reactjs app. In index.html add your script tag as you would in a normal app:


Then in the file you plan to use the library you can add a const and reference it normally:

const promisepay = window.promisepay;

Thanks to this link for the info: https://stackoverflow.com/a/44877953/522859

Allow Number and String for PropTypes – ReactJS

Hi everyone,

A quick post on how to allow a string or number when defining PropTypes:

static propTypes = {
        numberField: PropTypes.number.isRequired,
        stringField: PropTypes.number.isRequired,
        mixedField: PropTypes.oneOfType([PropTypes.string, PropTypes.number]).isRequired

Thanks to this stackoverflow post for the info: https://stackoverflow.com/a/41808543/522859