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@ariyahidayat

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Write programs that do one thing and do it well. Write programs to work together. Write programs to handle text streams, because that is a universal interface.

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{ type: "Program", body: [ { type: "VariableDeclaration", declarations: [ { type: "VariableDeclarator", id: { type: "Identifier", name: "answer" }, init: { type: "Literal", value: 42, raw: "42" } } ], kind: "var" } ] } var answer = 42;

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→

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function detect_console(code) { function check(node) { if (node.type === 'CallExpression') { if (node.callee.type === 'MemberExpression') { if (node.callee.object.name === 'console') { alert('console call at line', node.loc.start.line); } } } } var tree = esprima.parse(code, { loc: true }); estraverse.traverse(tree, { enter:check }); } http://ariya.ofilabs.com/2013/04/automagic-removal-of-javascript-logging.html

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reload(x, y, false) function checkLastArgument(node) { var args = node['arguments']; if (args.length < 2) { return; } if (typeof args[args.length - 1].value === 'boolean') { report(node, 'Dangerous Boolean literal'); } }

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http://ariya.ofilabs.com/2012/10/detecting-nested-ternary-conditionals.html var str = (age < 1) ? "baby" : (age < 5) ? "toddler" : (age < 18) ? "child": "adult";

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http://ariya.ofilabs.com/2012/12/complexity-analysis-of-javascript-code.html if (true) "foo"; else "bar";

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http://ariya.ofilabs.com/2013/05/continuous-monitoring-of-javascript-code-complexity.html

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“YOU SHALL NOT PASS!” — Darth Vader

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http://ariya.ofilabs.com/2013/01/javascript-code-complexity-visualization.html

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Non-Destructive Regenerative http://ariya.ofilabs.com/2013/06/javascript-source-transformation-non-destructive-vs-regenerative.html

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http://ariya.ofilabs.com/2012/02/from-double-quotes-to-single-quotes.html console.log('Hello') console.log("Hello")

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http://ariya.ofilabs.com/2013/05/es6-and-block-scope.html function f() { let j = data.length; console.log(j, 'items'); for (let i = 0; i < j; ++i) { let j = data[i] * data[i]; console.log(j); // squares } } function f() { var j = data.length; console.log(j, 'items'); for (var i = 0; i < j; ++i) { var j$0 = data[i] * data[i]; console.log(j$0); // squares } }

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Alice Bob Chuck Dan ... Bob Alice Dan Chuck ...

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Array.prototype.swap = function (i, j) { var k = this[i]; this[i] = this[j]; this[j] = k; } function sort(list) { var items = list.slice(0), swapped = false, p, q; for (p = 1; p < items.length; ++p) { for (q = 0; q < items.length - p; ++q) { if (items[q + 1] < items[q]) { items.swap(q, q + 1); swapped =true; } } if (!swapped) break; } return items; }

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http://ariya.ofilabs.com/2012/01/scalable-web-apps-the-complexity-issue.html Array.prototype.swap = function (i, j) { var k = this[i]; this[i] = this[j]; this[j] = k; } Array.prototype.swap = function (i, j) { Log({ name: 'Array.prototype.swap', lineNumber: 1, range: [23, 94] }); var k = this[i]; this[i] = this[j]; this[j] = k; }

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function inc(p, q) { if (q == undefined) q = 1; return p + q/q; } assert("inc(4) must give 5", inc(4) == 5); http://ariya.ofilabs.com/2012/12/javascript-code-coverage-with-istanbul.html

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http://ariya.ofilabs.com/2012/09/the-hidden-trap-of-code-coverage.html

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http://ariya.ofilabs.com/2013/05/hard-thresholds-on-javascript-code-coverage.html istanbul check-coverage --statement -5 --branch -3 --function 100

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“If you think JSLint hurts your feelings, wait until you use Istanbul.”

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...I gave you my heart But the very next day you gave it away...

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http://ariya.ofilabs.com/2012/12/quality-code-via-multiple-layers-of-defense.html

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Mr. Reviewer

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@ariyahidayat ariya.ofilabs.com/highlights speakerdeck.com/ariya Some artworks are from http://openclipart.org.