Updating wifi credentials to wpa_supplicant.conf in Rasberry Pi using Node.js

I am trying to provide wifi details to raspberry pi though Bluetooth.

We are adding the wifi credentials to /etc/wpa_supplicant/wpa_supplicant.conf file.

Once I get the credentials I am using nodejs to update the wifi credentials using fs.write(). I am completely overwriting the file. I am providing all the details needed in the file.

But I am getting the following error :

wpa_supplicant: /sbin/wpa_supplicant daemon failed to start
run-parts: /etc/network/if-pre-up.d/wpasupplicant exited with return code 1
Failed to bring up wlan0.

But when open the file in nano/vim I see that the file is getting written correctly. Am i missing something? My guess is that it might be the format in which I am writing.

I have an other question: What will happen if I keep on appending the file with the wifi credentials, instead of overwriting it?

Any help is greatly appreciated?

We found the problem why we were not able to provide wifi details. The reason was we were not writing the file properly. When creating the network variable, we were adding a space.

Error causing conf:

network={
        ssid ="WifiName"
        psk ="password"
}

Correct conf:

network={
        ssid="WifiName"
        psk="password"
}