Using Dev Tools

1. Getting Started with Dev Tools
March 2017
bit.ly/dc-dev-tools

2. About me
• Mohamed Chalal
• Developer at Signal Vine, previously at Ceretel
• Started my career in audio production
• Thinkful Mentor

3. About us
Thinkful prepares students for web development & data
science jobs with 1-on-1 mentorship programs

4. About you
• A lot of experience?
• A little experience?
• No experience?

5. Key Topics
• HTML/CSS Live Editing
• Mobile & responsive testing
• Editing with “Sources”
• Using the console
• Javascript Debugging
• Network performance

6. Setup — Download Chrome
• Standard for developers (Google!)
• Simple & polished
• Mobile & Desktop
• Firefox & Safari are OK
• Avoid Internet Explorer!

7. What are DevTools?

8. How do I open DevTools?
• Go to a page in Chrome
• Right Click => Inspect
• Also — Cmd + Shift + I

9. What are the benefits?
• Inspect Document Object Model (DOM)
• Update HTML/CSS in real-time
• Test responsive and mobile friendliness
• Run Javascript in console
• Test & debug Javascript
• Measure & improve performance

10. Why live editing for HTML/CSS?

11. Typical Workflow
• This style (or code) isn’t working!
• Open HTML/CSS/Javascript
• Guess where the problem is
• Make change
• Save change
• Refresh page
• Did it work?

12. Workflow with DevTools
• This style (or code) isn’t working!
• Open DevTools (“Inspect”)
• Make change
• Did it work?

13. What am I looking at?
DOM Styles

14. Live Editing HTML
• Inspect element
• Expand/Collapse
• Edit HTML
• Add attributes
• Click & drag
• Delete

15. Challenge
• Change your name to a friend’s name
• Try and change picture (advanced)
• Take a picture of their page
• Send to friend & say you hacked their account

16. Live Editing CSS
• See computed CSS styles
• CSS for states
• Add CSS properties
• Modify CSS properties
• Remove CSS properties
• Links to CSS source files

17. Challenge
• Change background to your favorite color
• Add a fun border to the post button
• Delete Newsfeed (advanced)

18. Sources Features
• Prettify
• Persistent changes
• Local modifications
• Revert
• Save As

19. Mobile Demo
• Responsive sizes
• Device
• Frame
• Media queries
• Rotate

20. Console Features
• Interact with page in real-time using Javascript

21. Console Demo
• Basic JS commands
• Grab/manipulate element
• Quick scrape

22. Challenge
• Go to https://dream-walker.herokuapp.com/
• Change the title using Javascript in the console

23. Javascript Debugging is Pain

24. Debugging Features
• See where Javascript is failing
• Inspect variables
• Step through code slowly

25. Debugging Demo
• http://samplerdj.com
• Add breakpoint (+ step through)
• Inspect variables
• Pause on caught & uncaught exceptions

26. Load times are important!
• Yahoo: reducing page load by .4 seconds increased
traffic by 9%
• Google: increasing page load times from .4 to .9
seconds decreased traffic by 20%
• Amazon: every .1 second increase in load time
decreases sales by 1%

27. Network Features
• Test load times
• Throttle to different speeds
• See which files are cached or not
• See which files are causing slowdowns
• See file download sequence
• Google PageSpeed!

28. Network Challenge
• Go to https://dream-walker.herokuapp.com/
• What is page load time?
• What files are causing slowdowns?
• What do you recommend as a fix?

29. Advanced Topics
• CPU profiling
• Memory profiling

30. More about Thinkful
• Anyone who’s committed can learn to code
• 1-on-1 mentorship is the best way to learn
• Flexibility matters — learn anywhere, anytime

31. Our Program
You’ll learn concepts, practice with drills, and build
capstone projects — all guided by a personal mentor

32. Our Mentors
Mentors have, on average, 10+ years of experience

33. Web Development Syllabus
• Frontend Development (HTML, CSS, Javascript)
• Frontend “Frameworks” (React.js)
• Backend Development (Node.js)
• Electives (Python, Ruby, Swift, Angular, UX)
• Computer Science Fundamentals
• Technical interviews + Career prep

34. Special Introductory Offer
• Two-week program, six mentor sessions for $50
• Starts with HTML/CSS/Javascript
• Option to continue into full program
• Talk to me (or email me) if you’re interested

35. October 2015
Questions?
Email Dan at dan@thinkful.com
Email me at mchalal@thinkful.com