Transform `Request` headers to plain key value object

I am trying to convert a list of headers from a Request (see https://developer.mozilla.org/en-US/docs/Web/API/Request/headers) object to a plain key/value object.

// Create a Request object.
const req = new Request('https://example.com', {
    headers: {
        'X-Test-header': 'Test'
    }
});

Sadly, the following doesn’t work because the headers property is an iterator:

Unusable result:

const result1 = JSON.stringify(req.headers);
// result1 =  `{}`

Usable result but very verbose to create:

const headers = {};
for(const [key, value] of req.headers.entries()) {
    headers[key] = value;
}
const result2 = JSON.stringify(headers)
// result2 = `{'X-Test-Header': 'Test'}`

I’m looking for some sort of a one liner (maybe including Array.from() or some of the other methods on the Request.headers object like .keys()/.values() so that I am able to stringify the result.

Answer

You could use the Object.fromEntries() method, and then stringify that object like below. The .fromEntries() method will invoke the iterator of your headers object (ie: the .entries()) to grab the entries of the header object, and then use that to create an object. You can then pass this to JSON.stringify() to get your JSON string:

const req = new Request('https://example.com', {
    headers: {
        'X-Test-header': 'Test'
    }
});

const result1 = JSON.stringify(Object.fromEntries(req.headers));
console.log(result1);