Can I DevTools?
  1. In the Sources tab, open the .js file from the the left sidebar. Set a breakpoint by clicking on the line number.
  2. Perform the action necessary to trigger that line of code, which will pause the execution at the breakpoint.
  3. Once activated, use the toolbar on the left sidebar (top) to step-in/step-out, watch expressions, local vars while debugging through the code.
  4. Alternatively, you can also add the debugger; statement in the code to pause execution of the code at that line.