NodeJS application Debugging

Core node.js debugger and node inspector

Using core debugger

Node.js provides a build in non graphical debugging utility. To start the build in the debugger, start the application with this command:

node debug filename.js

Consider the following simple Node.js application contained in the debugDemo.js

'use strict';
function addTwoNumber(a, b){
// function returns the sum of the two numbers
debugger
 return a + b;
}
var result = addTwoNumber(5, 9);
console.log(result);

The keyword debugger will stop the debugger at that point in the code.

Command reference

1. Stepping

cont, c - Continue execution
next, n - Step next
step, s - Step in
out, o - Step out

2. Breakpoints

setBreakpoint(), sb() - Set breakpoint on current line
setBreakpoint(line), sb(line) - Set breakpoint on specific line

To Debug the above code run the following command

node debug debugDemo.js

Once the above commands runs you will see the following output. To exit from the debugger interface, type
process.exit()

Conclusion

In this page (written and validated by A. Gawali) you learned about NodeJS application Debugging . What's Next? If you are interested in completing NodeJS tutorial, your next topic will be learning about: NodeJS server without framework.

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