Request with URL that includes credentials

I'm trying to fetch a curl and get a JSON from an API.

curl -XPOST -d "grant_type=password" -d "username=admin@admin.admin" \
    -d "password=admin" "web_app@localhost:8081/oauth/token"

When I use the curl in terminal everything works fine but trying it with a fetch I get the error message mentioned at the bottom.

fetch("http://web_app@localhost:8081/oauth/token", {
        credentials: 'include',
        body: "grant_type=password&username=admin@admin.admin&password=admin",
        headers: {
            "Content-Type": "application/x-www-form-urlencoded",
        },
        method: "POST"
    }

This is the error I get:

TypeError: http://web_app@localhost:8081/oauth/token is an url with embedded credentials.

Is the fetch I did wrong?

from Request with URL that includes credentials