Airbnb Javascript Style Guide

Given at the CCD session at RocketInternet - 10-05-2017

1. Airbnb JavaScript Style Guide() {

2. Code is first for human… not computer “

3. Why Style Guide? Best practices. More readable code Easy maintenance

4. Single standard? No, like a lot • Airbnb • Google • JQuery • W3Schools • Node • StandardJS We focus on Airbnb

5. References Use const or let for all of your references - avoid using var const and let only exist in the blocks they are defined in var is a function-scoped

6. Use one const or let declaration per variable Don't chain variable assignments Avoid using ++ , -- Variables

7. Literal syntax for object creation Don't use reserved words as keys Use object method shorthand Use property value shorthand Group your shorthand properties at the beginning of your object declaration. Objects

8. Use the literal syntax for array creation Use Array#push instead of direct assignment to add items to an array Use spread operator ... to copy arrays Arrays

9. Use single quotes '' for strings. Strings that cause the line to go over 100 characters should not be wrapped by concatenation When building up strings, use template instead of concatenation Do not unnecessarily escape characters in strings as backslashes harm readability Strings

10. Almost there ...

11. Use named function expressions instead of function declarations Function declarations are hoisted -- easy to use before it is defined in the file -- harms readability and maintainability Name the expression Wrap immediately invoked function expressions in parentheses Use default parameter syntax rather than mutating function arguments Functions

12. Put default parameters last Spacing in a function signature Never mutate parameters Never reassign parameters Multiline signatures should : each item on a line by itself trailing comma on the last item Functions

13. Use === and !== over == and != Use shortcuts for booleans, but explicit comparisons for strings and numbers Ternaries should not be nested and generally be single line expressions Avoid unneeded ternary statements Comparison & Equality

14. Don't use iterators Prefer higher-order functions map() / every() / filter() / … and Object.keys() / Object.values() / ... over loops like for-in , as this enforces immutability Iterators

15. Always comma-dangle (cleaner diff), even in function definition /** ... */ multi-line comments // for single line comments // FIXME: to annotate problems // TODO: to annotate solutions Commas, Comments

16. Guidelines use of EcmaScript 2015 features Modules import/export Class & extends String template notation Arrow functions Furthermore... Linters ESlint - Airbnb Style .eslintrc JSHint - Airbnb Style .jshintrc JSCS - Airbnb Style Preset CSS Airbnb CSS / Sass Styleguide

17. References https://github.com/airbnb/javascript