How to include local javascript on a Gatsby page?

 

After several hours of frustration I finally stumbled upon discussion on GitHub that solved this for me. In Gatsby, there is a thing called static folder, for which one use case is including a small script outside of the bundled code.

Anyone else in the same situation, try proceeding as follows:

1. Create a folder static to the root of your project.

2. Put your script script.js in the folder static.

3. Include the script in your react dom with react-helmet.

So in the case of the code I posted in my original question, for instance:

import React from "react"
import Helmet from "react-helmet"
import { withPrefix, Link } from "gatsby"

import Layout from "../components/layout"
import Image from "../components/image"
import SEO from "../components/seo"

const IndexPage = () => (
  <Layout>
    <Helmet>
        <script src={withPrefix('script.js')} type="text/javascript" />
    </Helmet>
    <SEO title="Home" keywords={[`gatsby`, `application`, `react`]} />
    <h1>Hi people</h1>
    <p>Welcome to your new Gatsby site.</p>
    <p>Now go build something great.</p>
    <div style={{ maxWidth: `300px`, marginBottom: `1.45rem` }}>
      <Image />
    </div>
    <Link to="/page-2/">Go to page 2</Link>
  </Layout>
)

Notice the imports

import Helmet from "react-helmet"
import { withPrefix, Link } from "gatsby"

and the script element.

<Helmet>
    <script src={withPrefix('script.js')} type="text/javascript" />
</Helmet>

This would have saved hours of my time, hopefully this does it for someone else.

const addExternalScript = (url, callback) => {
   const script = document.createElement('script');
   script.src = url;
   script.async=true;
   script.onload = callback;
   document.body.appendChild(script);
};

useEffect(()=>{
 addExternalScript("https://mapa.ecommerce.poczta-polska.pl/widget/scripts/ppwidget.js",window.PPWidgetApp.toggleMap())
},[])