Master the Art of the AST

A presentation at Full Stack Fest in September 2017 in Barcelona, Spain by Yonatan Mevorach

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//TODO Write linting rules to enforce your team’s code conventions ESLint ESTreebased AST Write your own javascript transpiling code Write powerful “code-mods” to automatically refactor thousands of legacy scripts from ES5 to ES6 + Visitor Pattern jscodeshift

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Webpack Babel Uglifyjs Rollup ESLint Istanbul Ternjs jscodeshift

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Abstract Syntax Tree cb http://flic.kr/p/gC4EkS

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var foo = 'bar'; Program Body Variable Declaration Kind Declarations Variable Declarator Id Init Identifier Literal

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var foo = 'bar'; { "type": "Program", "body": [ { "type": "VariableDeclaration", "declarations": [ { "type": "VariableDeclarator", "id": { "type": "Identifier", "name": "foo" }, "init": { "type": "Literal", "value": "bar" } } ], "kind": "var" } ] }