How can I get the private key from the generated RSA key object?

[coolKIH]

I am now wanting to program a web-based public-private key pair generator using javascript.
I am quite curious about how can I get public key from the private and know exactly what the private key is under the hood.

[blackdotroot]

rsa private key is consist of number n and d, public key is consist of number n and e.there is no method provided by cryptico to get private .