How to get body from post request?

Question

JavaScript

There is a code for sending a post request:

let data = new FormData()
        data["json"] = JSON.stringify(mydata);
        fetch(url, {
            method: 'POST',
            credentials: 'include',
            body: data
        }).then((res)=>{
            // ....
        }).catch(
//....
);

And there is code:

export async function post(req, res, next) {
    console.log(req.body)
    res.writeHead(200, {
        'Content-Type': 'application/json'
    });
}

But when outputting req.body it throws an error (underfined).
How can I get req.body?

Answer 1

Well, depending on what you use on the back-end, if express / koa then there is a body-parser in npm for them. If something else, then I think everything will be about the same there, except that the module will be called differently.
When using it as middleware in routing to this handler, everything will be in req.body

export async function post(req, res, next) {
    console.log(req.body) // вот для этого необходим body-parser
    res.writeHead(200, {
        'Content-Type': 'application/json'
    });
}