To debug the JavaScript, the developer can use the following three techniques:
Use console.log() messages in the JavaScript. The console.log() method is a built-in JavaScript function that prints a message to the browser's console. The developer can use this method to log the values of variables, parameters, or expressions in the JavaScript code, and check the console output for errors or unexpected results. The developer can also use other console methods, such as console.error(), console.warn(), or console.info(), to log different types of messages with different colors and icons.
Use the browser's dev tools to debug the JavaScript. The browser's dev tools are a set of tools that are integrated in the browser and allow the developer to inspect, modify, and debug the web pages. The developer can use the dev tools to debug the JavaScript code by setting breakpoints, stepping through the code execution, watching the variables, evaluating the expressions, and viewing the call stack. The developer can also use the dev tools to inspect the DOM elements, the network requests, the performance, and the storage of the web page.
Enable Debug Mode for Lightning components for the user. Debug Mode for Lightning components is a feature that allows the developer to debug the Lightning components more easily. When Debug Mode is enabled for a user, the Lightning components are served to the user in a more readable and unminified format, which makes the JavaScript code easier to understand and debug. The developer can also see more detailed error messages and stack traces when Debug Mode is enabled. The developer can enable Debug Mode for Lightning components for a user by going to Setup > Debug Mode, and selecting the user from the list. Reference: [Debug Your Code], [Use Browser Development Tools to Debug Your Code], [Debug Lightning Components]