Signer allows the user to sign or execute a transaction. Consider a Signer as the approval of the user. In order for the user the give his approval he requires to enter his PIN. A Signer will enable him to do so. venlyConnect.createSigner(…) as very first in your event handler otherwise, the popup might get blocked by the popup blocker of the browser.WindowMode you can close the Signer popup manually in case something went wrong. You can use the code snippet below to close it. The type guard, isn’t mandatory, but it makes the code more robust.