how can I pass success or error message using react-toastify when using axios method

I want to show success or error message depending upon the HTTP response status code that I will receiving upon sending my axios request ,using react-toastify (For example if the status code is 406 react-toastify should show a error message like "Some fields are empty" or if status code is "422" is should show a error message like "email already registered" and in case of status code "200" react-toastify should show a message "Account created successfully") on frontend.

Here is my backend api code

router.route('/register').post(upload.single('photo'), (req, res) => {

  const name = req.body.name;
  const email = req.body.email;
  const phone = req.body.phone;
  const work = req.body.work;
  const password = req.body.password;
  const cpassword = req.body.cpassword;
  const photo =  req.file.filename;

  
  if(!name || !email || !phone || !work || !password || !cpassword || !photo ){
    return res.status(406).json({message:"Some fields are missing"}) ;
    
}
  User.findOne({email: email})
  .then((userExist)=>{
         if (userExist){
             return res.status(422).json({Error:"Email already registered"});
            
       }

       const newUserData = {
        name,
        email,
        phone,
        work,
        password,
        cpassword,
        photo
    }

    const newUser = new User(newUserData);
       newUser.save().then(()=>{
        res.status(201).json({message:"user created successfuly"});
        alert("user created succcessfully")
             }).catch((err)=>res.status(500).json({error:"registeration failed"})
             );
         }).catch((err)=>{console.log(err);});
         
         });

Here is the function on front that fetch data from input field

   const handleSubmit = (e) => {
        e.preventDefault();
        let url = 'http://localhost:3000/register'
        const formData = new FormData();
        formData.append('name', newUser.name);
        formData.append('email', newUser.email);
        formData.append('phone', newUser.phone);
        formData.append('work', newUser.work);
        formData.append('password', newUser.password);
        formData.append('cpassword', newUser.cpassword);
        formData.append('photo', newUser.photo);

        axios.post(url , formData)
             .then(res => {
                console.log(res)
                history.push('/login')
                
             } )
             .catch(err => {
                console.log(err);
                
             });
    }

Assuming you already have react-toastify setup, just check the response status and trigger toast if it's equal to the value you want, 200 in your case. Like this:

 axios.post(url , formData)
     .then(res => {
        if (res.status === 200)
          toast.success("Success!");

        history.push('/login')
                
        } )
     .catch(err => {
        console.log(err);
                
     });

Edit: If it's the newUser function you are calling, the status on POST requests will be 201 when they succeed, opposed to 200, which you mentioned in the question. If that's the case, just replace 200 with 201.