Support more fine grained fetchRequestInit options

[wkelly1]

The fetchRequestInit options available on the conversion functions are only available as a global option. The logic for this can be found here: https://github.com/bubkoo/html-to-image/blob/master/src/dataurl.ts#L86.

For the general case this is fine however there are cases where you need to set specific options per request. For example, if you have two images within the DOM nodes that you are converting, one that requires credentials but another that doesn't and has Access-control-Allow-Origin set to * then the conversion will fail due to CORS restrictions. There are likely other cases where this is important.

Expected Behaviour

The fetchRequestInit options should allow you to specify the options per resourceUrl which would give the user full control over how the request is handled.

Possible Solution

Te fetchRequestUrl should support the ability to be a function that takes the parameter resourceUrl and returns the RequestInit options.

e.g.

fetchRequestInit: RequestInit | (resourceUrl: string) => RequestInit

This would let the user then do:

fetchRequestInit: (resourceUrl) => {
  if (resourceUrl === "https://example.com/...") {
     return {
       credentials: "include"
     }
  }

  return {
    credentials: "omit"
  }
}

This would then also be backwards compatible without a breaking change.

[biiibooo]

👋 @wkelly1

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