Error "Unexpected token P in JSON at position 0 in fetch" - json

Question

I created a signup form, In this I'm posting data from react client to the node server where I created a signup route to handle that signup form.
Here we are posting data to the server.
async function submitHandler(e){
e.preventDefault();
try{
const response = await fetch("/signup", {
method: "POST",
body: JSON.stringify({
name: name,
email: email,
password: password
}),
headers: {
"Content-Type": "application/json"
}
})
console.log(response);
const data = await response.json();
if(data.error){ //This code of line to make sure that if there is any error then it should be catchable by the catch block.
throw new Error(data.error);
}
}
catch(e){
console.log(e.message); //Here I'm getting error -> unexpected token p in JSON at position 0.
}
}
This is the route where I'm posting data.
router.post("/signup", async(req, res) => {
const {name, email, password} = req.body;
try{
const XYZ = await User.ValidatingUser(name, email, password); //Here we are calling a function to check email exist or not before create an account.
const user = new User({
name: name,
email: email,
password: email
})
await user.save();
return res.send("Posted successfully");
}
catch(e){
return res.json({error: e.message});
}
})
This is the function which I'm calling in the signup route to check email is exists or not.
//This code is to check that email exists or not. If the email exists then you can't signup.
userSchema.statics.ValidatingUser = async(name, email, password) => {
if(!name || !email || !password){
throw new Error ("Please add all the fields");
}
const user = await User.findOne({email: email});
if(user){
throw new Error("That email is already exist");
}
}
When I click on the signup submit button, first it shows error -> unexpected token P in JSON at position 0.
But When I again clicked on the signup submit the form then it will show this error -> That email already exists (which is returned by our server).
So it means data is saving in our DB.
See this Image.
enter image description here

Answer 1

I find it.
It was difficult but it's res.send("Posted successfully"); the issue.
You are to send a string as JSON, which is NOT JSON.
So, basically you have to do like:
res.send({message: "Posted successfully"});
Just: try to don't duplicate.