JSBridge is not defined

I followed the following documentation to integrate the JavaScript Bridge Library in my web application - https://median.co/docs/javascript-bridge

Upon integrating the GoNativeJSBridgeLibrary file into my project and trying to utilize its provided methods, I came across an issue. The problem arises when I attempt to call the addCommand function, specifically in the last line where JSBridge.postMessage(data) is written. The error message indicates that JSBridge is not defined. I am unsure about what JSBridge refers to and whether it is a separate library that should be added or installed. I am wondering if there might be a step or point in the process that I have overlooked.

The error I am encountering is as follows.

gonative.js:83 Uncaught (in promise) ReferenceError: JSBridge is not defined at addCommand (gonative.js:83:3) at gonative.js:20:4