Advanced Node.js Linting with ESLint

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ESLINT ADVANCED LINTING IN NODE.JS USING

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LINTING WHY CARE ABOUT

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YOU’RE MISSING  A SEMI-COLON PAIR PROGRAMMING I USE STANDARD  YOU IDIOT

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LINTING MULTIPLIES YOUR POWER AS A LEAD ENGINEER Jamund Ferguson WHY CARE ABOUT LINTING?

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PATTERNS RECOGNIZING AND ENFORCING

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PATTERN ERROR HANDLING

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ERROR HANDLING CALLBACK THROW PROMISE THESE ARE NOT ERRORS!

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ERROR HANDLING

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PATTERN CALLBACK

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CALLBACK PATTERN WHERE’S THAT  ERROR-FIRST? UNHANDLED  ERROR UNHANDLED  ERROR

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CALLBACK PATTERN

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PATTERN PROMISE

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PROMISES

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PROMISES

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PATTERNS MISMATCHED

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PATTERN MISMATCH: PROMISES VS. CALLBACK PATTERN CALLBACK PATTERN PROMISES

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PATTERN MISMATCH: PROMISES VS. CALLBACK PATTERN MISSING ERROR HANDLER

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PATTERN MISMATCH: PROMISES VS. CALLBACK PATTERN

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PATTERN MISMATCH: PROMISES VS. CALLBACK PATTERN CALLBACK VERSION PROMISE VERSION

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PATTERN MISMATCH POTENTIAL MISMATCHED PATTERNS ▸ ES6 Classes, Prototypes ▸ ES6 modules, CommonJS modules, AMD modules ▸ Connect middleware, Koa middleware, Alternatives… ▸ Early return, single in single out ▸ Factory, Singleton, etc. ▸ Lodash, Underscore or other competing modules

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ESLINT RULES CREATING CUSTOM

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astexplorer.net ABSTRACT SYNTAX TREE SOURCE CODE

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ABSTRACT SYNTAX TREES: FUNCTIONS

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ABSTRACT SYNTAX TREES: FUNCTIONS

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ABSTRACT SYNTAX TREES: PROMISES

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astexplorer.net

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SOURCE CODE ABSTRACT SYNTAX TREE RULE CODE ESLINT OUTPUT

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NO PROMISES IN CALLBACKS CUSTOM ESLINT RULE

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CUSTOM LINT RULE: NO PROMISES INSIDE CALLBACKS CALLBACK PROMISES

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TEXT

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HOW WE DETECT A PROMISE CUSTOM LINT RULE: NO PROMISES INSIDE CALLBACKS

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HOW ERROR REPORTING WORKS IN ESLINT RULES CUSTOM LINT RULE: NO PROMISES INSIDE CALLBACKS

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TEXT CLICK HERE

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TEXT

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TEXT DETECTING A PARENT CALLBACK FUNCTION

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TEXT

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TEXT NO ERORS NO CALLBACKS

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DETECT CALLBACK DETECT PROMISE REPORT ERROR

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ADVANCED LINTING IN NODE.JS USING ESLINT WHAT YOU NEED TO REMEMBER ▸ Recognize the patterns used in your code and make sure they’re being applied correctly ▸ Learn ASTs to help you succeed ▸ Apply lint rules that help you enforce best practices ▸ Create and share custom lint rules to scale your impact