html-form-enhancer

1. enctype="application/json" or an enctype with the pattern application/*+json.
2. method is something other than POST or GET.

If you want to take advantage of the form enhancer for your other forms, you need to
manually use the enhanceForm function on it.

After enhanceForm takes over a , it hooks into the submit event.

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1. If the method was GET or DELETE, take all form fields and place them in
the uri.
2. Otherwise, serialize the fields into the body. Use normal form serialization
for application/x-www-form-urlencoded and use the [html-json-forms][1] spec
for all JSON forms.

Note: multipart/form-data is not yet supported.

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The actual submission is done with fetch(). This means that if you do
cross-origin requests, CORS headers _must_ be set correctly.

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#### 201 Created

If the HTTP response is 201 Created and contains a Location header, it
will _not_ redirect the browser. It will take the Location value and place
it in the action attribute, and will change the method to PUT.

This is especially useful if you are using POST for creating new resources
and want to be able to use PUT afterwards to update the resource.


#### 204 No Content

If the HTTP Response is 204 No Content, it won't redirect and will allow
the user to make subsequent edits and submissions.


#### 205 Reset Content

If the server responded with 205, it will call the forms .reset()
function. The effect is similar to pressing a button.

This is useful for submitting a bunch of forms in a row.


#### 3xx responses

If the HTTP response is in the 3xx category, it will read the Location`
header and redirect the browser to the specified location.

#### Other HTTP responses

Other HTTP responses will result in the entire HTML body to be replaced with
the body returned from the server.

[1]: https://www.w3.org/TR/html-json-forms/