Developing large apps is difficult. Ensuring that code is consistent, well structured, tested and has an architecture that encourages enhancement and maintainability is essential. When it comes to building large server-focused apps the solutions to this problem have been tried and tested. But, how do you achieve this when building HTML5 single page apps?
BladeRunnerJS is an open source developer toolkit and lightweight front-end framework that has helped Caplin Systems ensure that a 200k LoC JavaScript codebase hasn’t become a tangled mess of unstable spaghetti code. This codebase is packaged and delivered to customers as an SDK. Additionally customers receive a getting started application of around 50k LoC for them to build upon, and they’re expected not to turn that into a tangled … you get the idea.
In this talk you’ll learn the main concepts to apply when building a front-end app that scales and how BladeRunnerJS can support the development process.
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Using BladeRunnerJS to Build Front-End Apps that Scale - Fluent 2014
7. –Addy Osmani, Patterns For Large-Scale JavaScript Application
Architecture
In my view, large-scale JavaScript apps are
non-trivial applications requiring significant
developer effort to maintain, where most heavy
lifting of data manipulation and display falls to
the browser.
9. Caplin Trader
• SDK:
• ~1,000 JavaScript files
• ~131,000 LoC
• ~131 lines per file
• ~650 test files
• ~95,000 test LoC
• Typical Apps:
• ~425 JavaScript files
• ~50,000 LoC
• ~117 lines per file
• ~200 test files
• ~21,000 test LoC
15. Who contributes to an app?
• Front-end devs
• Back-end devs
• Designers
• QA
• Infrastructure and release engineers
• Technical authors
16. So, how do you ensure an
application is maintainable?
1. structure a massive codebase (js, css, html, i18n,
images, config etc.)
2. an architecture for complex functionality and
interaction (UI and other components)
3. make sure that all contributors can work in harmony
4. development must be a productive experience
5. ensure all these compliment each other
19. My App isn’t working!
• Other contributors breaking functionality
• Code accessed and modified from elsewhere
• Dependency Analysis and out of order file concatenation
23. Have the tests finished yet?
• Having to run all the tests
• UI-based tests: Slow & unreliable
• Continuous Integration…taking 8 hours!
Stopwatch designed by Irit Barzily from the thenounproject.com
25. • Streamlined developer workflow
• Consistency
• Focus on building a single feature (in isolation)
• Scalable loosely-coupled application architecture
• Quality at its core (maintainability)
BRJS Goals
38. • Streamlined developer workflow
• Consistency
• Focus on building a single feature (in isolation)
• Scalable loosely-coupled application architecture
• Quality at its core (maintainability)
Goals
40. Requires an Architecture
that…
• Allows complex interactions
• Support developing a feature in isolation
• Allows components to be changed without side effects
• Is to maintain: Fix / Update / Extend
44. What is a service?
• Use services to access shared resources
• Persistence Service
• RESTful Service
• Realtime Service
• Services registered and accessed via a ServiceRegistry
• Dynamic Service Locator1
1 http://martinfowler.com/articles/injection.html#ADynamicServiceLocator
45. Why use services?
• Blades should not directly communicate
• Functionality encapsulated behind an interface
• Loose-coupled communication
• Dependencies can be injected for different scenarios:
• Workbench / Test / App
48. • Streamlined developer workflow
• Consistency
• Focus on building a single feature (in isolation)
• Scalable loosely-coupled application architecture
• Quality at its core (maintainability)
Goals
53. Biggest Win
• Testing features in
isolation
• Change view model
and assert against
mocked Service
• Inject mock service,
make calls and assert
View Model
55. Need Proof?
Our full suite Caplin Trader
testing time went from
>8 Hours
< 30 minutes
Much less for a single
feature
56. • Streamlined developer workflow
• Consistency
• Focus on building a single feature (in isolation)
• Scalable loosely-coupled application architecture
• Quality at its core (maintainability)
Goals
57. Summary
• BladeRunnerJS toolkit: Streamline developer
workflow + focus on features
• Blades: Build features in isolation (grouping assets
together)
• Services: loose coupled communication e.g. EventHub
• Quality: Test units (classes), features (ViewModel < - >
Service) & keep DOM testing to a minimum.
58. BRJS at Fluent
• BladeRunnerJS is a new open source solution
• bladerunnerjs.org
• v0.4 released last week
• @leggetter & @patrickmyles are at Fluent today &
tomorrow
• BoF session tomorrow - table #7