SEP007 Stellar-JS-SDK Integration
As part of the protocol outlined in SEP007, to create a uri without a known source account beforehand, you must specify the source account in the XDR as all zeros.
xdr (required) - A Stellar transaction in XDR format that is base64 encoded and then URL-encoded. If the source account in the xdr is all zeros then the URI handler should replace the source account and sequence number with the user's source account and sequence number before it signs it. If the source account is set and the sequence number is 0 then the URI handler should replace only the sequence number before signing.
Currently this is not possible in the Stellar-JS-SDK.