JS Code Kata: Linked List

We use TDD and a simplified version of the Transformation Priority Premise to implement Linked List in JavaScript

Code: https://github.com/yitznewton/linked_list_js

References:

https://blog.8thlight.com/uncle-bob/2013/05/27/TheTransformationPriorityPremise.html

https://cleancoders.com/category/advanced-tdd

Transcript

1. JS
2. Prerequisites • node.js (e.g. `brew install node`)
3. JS libraries • Mocha (test framework) • Chai (assertions) • Sinon (test doubles)
4. Other useful JS libraries • eshint (code linter) • underscore (FP helpers) • q (async promises) • karma (test runner)
5. Code Kata Japanese: form
6. Linked List
7. Linked List var first = { value: 12 }; var second = { value: 99 }; var third = { value: 37 }; first.next = second; second.next = third;
8. Linked List var list = new LinkedList(); list.append(12); list.append(99); list.append(37); list.each(function(v) { console.log(v); }); // log: 12 99 37
9. Object Behavior • Return a value • Send a message to another object • Change internal state When receiving a message:
10. Testing Object Behavior When receiving a message: • Return a value • Send a message to another object • Change internal state
11. Linked List var list = new LinkedList(); list.append(12); list.append(99); list.append(37); list.each(function(v) { console.log(v); }); // log: 12 99 37
12. TDD • No production code which does not make a failing test pass • Stop writing test code once there is enough to fail • No more production code than will make the test pass
13. Transformations Refactor
 change form without changing behavior Transform
 change behavior while changing form as little as possible
14. Transformations • None • One • Many
15. Transformations Tranformation
 Priority Premise Transformations emerge
 in a logical sequence
 as the code evolves
16. Transformations Tranformation
 Priority Premise Transformations emerge
 in a logical sequence
 as the code evolves specific → generic