WarsawJS Presentation: Template

Piotr Zientara

Debugging JS

2015-09-16

@Piotr_Zientara

Why do we need to debug?

Often, when JavaScript code contains errors, nothing will happen. There are no error messages, and you will get no indications where to search for errors.

source: W3 Schools

#debuggingJS

Methods of debugging

Console logs and alerts
Debugger
Examining the code
Learning more about framework and methods we use
Deleting code

What caused that bug?

Logging methods

See if the code executes
Check the variables
Rembember to remove the logs!

Sad developer's console

Examining code

Clean and refactor your code
Hunt for typos
Change the order of code execution

On load vs on ready

                $( document ).ready(function() {
                  // code 1
                })

                $( window ).load(function() {
                  // code 2
                })

Learn about methods and your framework

The differences can be tricky
Maybe some methods just work by accident?
Debug yourself ;-)

Usuall error

Difficult detection?

The double miracle

Why we make typos?

Clumsy fingers?
Bad habbit?
Cultural thing?

Do you want to be a ninja programmer?

Fulfil your dreams!

Visit Geek Typer

The debugger tool in modern browsers

Stops execution of the code
Multiple breaks can be set
Can be turned on automaticly on any exception

Removing code methods

when all methods fail, the new plan A!

Delete suspecious code
Delete the code using bisect
Recreate the error in a smaller environment
Delete the code and write it again

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