Why is node.js fetch giving a 'Bad Request' error? - node.js

Question

I am getting a 400 error (bad request) from this POST:
siteData.myPost = async function (url, data) {
let options = {
method: 'POST',
headers: {
'Content-Type': 'application/json;charset=utf-8'
},
body: JSON.stringify(data)
}
try {
const response = await fetch(quilkinUrlBase() + url,options);
return response.json();
}
catch (error) {
qPopup.Alert("Error with web request: " + error);
}
};
(the fetch address computes to "http://localhost:1337/UpdateSiteVisits").
This can't, of course, convert 'response' to json because the response is a DOC containing the 400 error message.
in server.js I have the following callback definition for the URL specified in the fetch:
app.post("/UpdateSiteVisits", sites.updateVisits);
in the debugger, the code never reaches updateVisits().
I have a very similar construct with a GET:
app.get("/GetSitesForType/:type", sites.findByType);
which works fine, so I assume the problem is with the 'options' object (which the GET doesn't use). In the POST case the data is just an integer ID, and if I change the data format to plain text (instead of json), the post works fine.
If leave the format as json, and send an object, rather than a simple integer, the post also works fine. So it looks like the system just doesn't like converting a single integer to json.

Answer 1

I needed to send the integer as json, so instead of using the method like this:
siteData.myPost("UpdateSiteVisits", siteID)
I needed to use
siteData.myPost("UpdateSiteVisits", { siteId: siteID })
[ later ]
Please ignore my question and answer, I was just getting mixed up with types. Such is the result from me converting from strongly-typed C# to untyped javascript!