Making JavaScript Libraries More Approachable

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.)

Transcript

1. WHY NESTED TERNARY OPERATORS MAKE ME WANT TO KICK INANIMATE OBJECTS IN THE NUTS AKA: Making JavaScript Libraries More Approachable Pamela Fox @pamelafox http://tinyurl.com/ternaryops
2. IN THE WORLD OF JS LIBRARIES... USERS AUTHORS
3. I'VE BEEN USING A LOT OF LIBRARIES THIS PAST YEAR... bootstrap.datepicker.js bootstrap.js colorslider.js confetti.js date.format.js dateinput.js dd_belatedpng.js facebook.js facebook_js_sdk.js handlebars.js highcharts.js jquery-1.7.min.js jquery.autosuggest.js jquery.calendrical.js jquery.dateinput.js jquery.fancybox.js jquery.mobile.js jquery.overlay.js jquery.sparkline.js jquery.tablesorter.js jquery.tagfield.js jquery.tooltip.js jsrender.js lscache.js modernizr-1.7.js personalize.js phonegap.js stacktrace.js throttle.js timeago.js useragent.js zepto.js
4. AND SOMETIMES I SEE STUFF LIKE... (aposed ? (aposed = !apos, (aposed ? all : '"')) : quoted ? (quoted = !quot, (quoted ? all : '"')) : ( (lftPrn ? (parenDepth++, lftPrn) : "") + (space ? (parenDepth ? "" : named ? (named = FALSE, "\b") : "," ) : eq ? (parenDepth && syntaxError(), named = TRUE, '\b' + path + ':') : path ? (path.replace( rPath, parsePath ) + (prn ? (fnCall[ ++parenDepth ] = TRUE, prn) : operator) ) : operator ? all : rtPrn ? ((fnCall[ parenDepth-- ] = FALSE, rtPrn) + (prn ? (fnCall[ ++parenDepth ] = TRUE, prn) : "") ) : comma ? (fnCall[ parenDepth ] || syntaxError(), ",") : lftPrn0 ? "" : (aposed = apos, quoted = quot, '"') ))
5. AND IT MAKES ME THINK OF....
6. ...WOULDN'T THIS BE BETTER?
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.
9. NOT ENOUGH DOCUMENTATION. this.options.knownHelpers = { 'each': true, 'if': true, 'unless': true, 'with': true, 'log': true }; handlebars.js
10. TOO MUCH DOCUMENTATION. vs. https://github.com/wycats/handlebars.js/ http://handlebarsjs.com/
11. DUPLICATE DOCUMENTATION. vs.
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. var a = s.split("."), 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.
17. MISSING SEMI-COLONS.
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." "Relying on implicit insertion can cause subtle, hard to debug problems. Don't do it. You're better than that." Google Style Guide Jason Kester
19. MISSING SEMI-COLONS. AGAINST: It's harder to make non-breaking changes to the code. a = b + c (d + e).print() a = b + c(d + e).print(); is interpreted as: so you have to: ;(d + e).print() this:
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.
21. MISSING SEMI-COLONS. AGAINST: Hacker News agrees.
22. NESTED TERNARY OPERATORS. $.qsa = $$ = function(element, selector){ var found return (element === document && idSelectorRE.test(selector)) ? ( (found = element.getElementById(RegExp.$1)) ? [found] : emptyArray ) : (element.nodeType !== 1 && element.nodeType !== 9) ? emptyArray : slice.call( classSelectorRE.test(selector) ? element.getElementsByClassName (RegExp.$1) : tagSelectorRE.test(selector) ? element.getElementsByTagName (selector) : element.querySelectorAll(selector) ) } zepto.js
23. NESTED TERNARY OPERATORS. AGAINST: They're hard to understand. $.qsa = $$ = 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.
29. TOO MANY TOOLS?
30. WHICH ONE DO YOU WANT TO BE? vs. SO, IF YOU'RE A LIBRARY... USERS AUTHORS USERS AUTHORS elite approachable