Check if monetization is enabled on a website

[sharon-wang]

Fixes: #5, fixes: #10

• Check for monetization meta tag
• Resolve specified payment pointer
• Verify that resolved payment pointer is valid

Open up the console to check if the site is monetized, what the payment pointer is and what the resolved payment pointer is.

Note that the http request is currently synchronous, which is deprecated:

Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check https://xhr.spec.whatwg.org/.

Opened an issue: #10 to note that we should fix this. Ignoring for now since we have a backlog for the prototype.

[sharon-wang]

To fix #10 in this PR, I will:

1. Add an async init() function which contains a variable = await isMonetizationPresent()
2. All functions except resolvePaymentPointer() will be async
3. Add await to each async function as appropriate
4. httpGet() will use fetch() API instead of the deprecated XMLHttpRequest()

Big thanks to @vezwork for referencing and explaining fetch and promises

[sharon-wang]

@vezwork This PR is ready for review!

Added fetch API to handle async http, which fixes #10.

[sharon-wang]

Just read over the SPSP Spec, I think I'm missing this:

Raw endpoint URL (Not recommended) https://example.com/spsp/alice. This SHOULD NOT be exposed to users, but SHOULD be supported by SPSP Clients.

This to me sounds like raw endpoint URLs (https://host.com/path) might be used in the monetization meta tag instead of a payment pointer ($host.com/path).

@vezwork What do you think?

[vezwork]

Looks great

[vezwork]

Just read over the SPSP Spec, I think I'm missing this:

Raw endpoint URL (Not recommended) https://example.com/spsp/alice. This SHOULD NOT be exposed to users, but SHOULD be supported by SPSP Clients.

This to me sounds like raw endpoint URLs (https://host.com/path) might be used in the monetization meta tag instead of a payment pointer ($host.com/path).

@vezwork What do you think?

Good to make note of, but I don't think it's worth worrying about unless we come across a problem caused by this. We could add an issue with a low priority tag for this?

[sharon-wang]

Good to make note of, but I don't think it's worth worrying about unless we come across a problem caused by this. We could add an issue with a low priority tag for this?

Added #11 with a low priority tag so we can look into this later on :)

[sharon-wang]

@vezwork fixed the typo and added a link to Interledger SPSP Endpoint Specification. Merging!