A talk given at NotConf in Phoenix, Texas in 2012.
(Alternative title: Why nested ternary operators make me want to kick inanimate objects in the nuts.)
The Codex of Business Writing Software for Real-World Solutions 2.pptx
Making JavaScript Libraries More Approachable
1. WHY NESTED
TERNARY OPERATORS
MAKE ME WANT TO
KICK INANIMATE
OBJECTS IN THE NUTS
AKA: Making JavaScript Libraries More Approachable
http://tinyurl.com/ternaryops
Pamela Fox
@pamelafox
7. THE STAGES OF BEING A USER:
1. Learn how a library works & start using it.
2. Debug a library when something goes wrong.
3. Integrate a library with their workflow.
4. BONUS: Submit a patch to the library.
8. STEP 1: THIS LOOKS LIKE A USEFUL
LIBRARY, LET'S SEE HOW TO USE IT.
Document everything.
JSDoc, JSDuck, JoDoc, Dox, NDoc,
Docco, Docco-Husky,
AutoObjectDocumentation
Make the documentation easy to patch.
12. STEP 2: UH OH, SOMETHING WENT
WRONG. TIME TO DEBUG THE LIB.
Make your code readable.
○ "Common conventions"
■ Idiomatic.js
■ Crockford
■ Google
■ Stoyan Stefanov
○ Descriptive variable names
Make your code debuggable.
○ On *all* platforms.
13. SHORTENED VARIABLE NAMES.
ar a = s.split("."),
v
r = "",
l = a.length;
for (var i = 0; i < l; i++) {
var item = a[i];
if (item.length == 2) {
r += "0" + item;
} else {
r += item;
}
}
function login(a, b) {
b = b || { perms: '' };
PhoneGap.exec(function(e) {
FB.Auth.setSession(e.session, 'connected');
if (a) a(e);
}, null, 'com.phonegap.facebook.Connect', 'login', b.
perms.split(',') );
}
14. SHORTENED VARIABLE NAMES.
FOR:
The shortened names make sense.
AGAINST:
Maybe to you. But not to people new to the
code.
"Common sense" is not common.
15. SHORTENED VARIABLE NAMES.
FOR:
It makes for less bytes of code.
AGAINST:
Code will get compiled to least number of
bytes anyway.
16. SHORTENED VARIABLE NAMES.
FOR:
It makes for shorter lines of code.
AGAINST:
Readability trumps line length.
18. MISSING SEMI-COLONS.
AGAINST:
It's harder to read the code.
"Readability is the single most important quality of a
piece of code. Semicolons aid readability by eliminating
ambiguity and ensuring that nobody ever has to spend
even a second figuring out whether your code will do
what it looks like it will do."
Jason Kester
"Relying on implicit insertion can cause subtle, hard to
debug problems. Don't do it. You're better than that."
Google Style Guide
19. MISSING SEMI-COLONS.
AGAINST:
It's harder to make non-breaking changes
to the code.
this:
a = b + c
(d + e).print()
is interpreted as:
a = b + c(d + e).print();
so you have to:
;(d + e).print()
20. MISSING SEMI-COLONS.
FOR:
It's what the core team prefers.
AGAINST:
The core team aren't the only developers
looking at the code. (But they might be if
that's the philosophy.)
Don't use your library code to show off how well you
know the idiosyncrasies of a language.
23. NESTED TERNARY OPERATORS.
AGAINST:
They're hard to understand.
$.qsa = $$ = function(element, selector){
var found;
if (element === document && idSelectorRE.test(selector)) {
found = element.getElementById(RegExp.$1);
return found && [found] || [];
} else if (classSelectorRE.test(selector)) {
return slice.call(element.getElementsByClassName(RegExp.$1));
} else if (tagSelectorRE.test(selector)) {
return slice.call(element.getElementsByTagName(selector));
} else {
return slice.call(attemptQuerySelectorAll(element, selector));
}
}
If you have the choice between two styles and
one is more readable, choose that one.
24. NESTED TERNARY OPERATORS.
AGAINST:
It's hard to debug the nested statements.
FOR:
You can debug them with breakpoints.
AGAINST:
You can't always use fancy debuggers.
See: Android, IE
25. NESTED TERNARY OPERATORS.
FOR:
They perform better than if/else.
AGAINST:
Compilers convert if/else to ternary.
Try in UglifyJS or Closure Compiler.
26. STEP 3: OK, ALL WORKING. TIME TO
INTEGRATE WITH MY WORKFLOW.
Try your code with popular JS build tools
● JSHint
● Closure Compiler / UglifyJS
● Grunt
If it requires options, specify them or inline
them into the code.
27. UNSPECIFIED JSHINT OPTIONS.
[jshint] Error(s) in ./application/static/js/libs/bootstrap.js:
Missing semicolon. (line: 24, character: 5)
> "use strict"
Comma warnings can be turned off with 'laxcomma' (line: 31, character: 9)
> , thisStyle = thisBody.style
Bad line breaking before ','. (line: 30, character: 48)
> var thisBody = document.body || document.documentElement
...
Too many errors. (8% scanned). (line: 139, character: 73)
/*jshint asi:true, laxbreak:true, laxcomma:true, expr:true, boss:true */
28. STEP 4: WHEE, IT WORKS, NOW I JUST
WANNA SUBMIT THIS ONE CHANGE.
Make it easy to build.
Make the tests easy to run.
...use familiar tools and languages.