Testing a cloudflare worker with HTMLRewriter fails as its undefined - cloudflare

Question

I have a test to test my cloudflare worker that looks like this:
const workerScript = fs.readFileSync(
path.resolve(__dirname, '../pkg-prd/worker.js'),
'utf8'
);
describe('worker unit test', function () {
// this.timeout(60000);
let worker;
beforeEach(() => {
worker = new Cloudworker(workerScript, {
bindings: {
HTMLRewriter
},
});
});
it('tests requests and responses', async () => {
const request = new Cloudworker.Request('https://www.example.com/pathname')
const response = await worker.dispatch(request);
console.log(response);
// const body = await response.json();
expect(response.status).to.eql(200);
// expect(body).to.eql({message: 'Hello mocha!'});
});
});
In my worker I do something like this:
const response = await fetch(BASE_URL, request);
const modifiedResponse = new Response(response.body, response);
// Remove the webflow badge
class ElementHandler {
element(element) {
element.append('<style type="text/css">body .w-webflow-badge {display: none!important}</style>', {html: true})
}
}
console.log(3);
return new HTMLRewriter()
.on('head', new ElementHandler()).transform(modifiedResponse);
Now when i run my test I get this error message:
● worker unit test › tests requests and responses
TypeError: Cannot read property 'transform' of undefined
at evalmachine.<anonymous>:1:1364
at FetchEvent.respondWith (node_modules/#dollarshaveclub/cloudworker/lib/cloudworker.js:39:17)
What seems to be wrong?
HTMLRewriter i created looks like this:
function HTMLRewriter() {
const elementHandler = {};
const on = (selector, handler) => {
if (handler && handler.element) {
if (!elementHandler[selector]) {
elementHandler[selector] = [];
}
elementHandler[selector].push(handler.element.bind(handler));
}
};
const transform = async response => {
const tempResponse = response.clone();
const doc = HTMLParser.parse(await tempResponse.text());
Object.keys(elementHandler).forEach(selector => {
const el = doc.querySelector(selector);
if (el) {
elementHandler[selector].map(callback => {
callback(new _Element(el));
});
}
});
return new Response(doc.toString(), response);
};
return {
on,
transform
};
}

Answer 1

Since HTMLRewriter() is called with new, the function needs to be a constructor. In JavaScript, a constructor function should set properties on this and should not return a value. But, your function is written to return a value.
So, try changing this:
return {
on,
transform
};
To this:
this.on = on;
this.transform = transform;