[bgidley]

It can prevent MITM IF it's loaded in client page (defining MITM as network interception).

It can't stop keyloggers, people looking over your shoulder, malware in the browser (MITB)/plugins as it still sits within the browser sandbox. It can in some cases detect that, and in some cases hinder it.

An attacker can stop it loading by MITM the connection, but then the site can't work against it's APIs as the solution also verifies as data goes into those API's the encryption is present and the code isn't tampered. If it's tampered a business rule is applied to decide what to do, either stop the messages, OR pass it back to risk management systems (very common in finance).