Not doing so will result in global variables. 26.4 Use find with scoped jQuery object queries. contains utilities that are functionally broken but remain for legacy reasons. Always define explicit defaultProps for all non-required props. If you find that a function’s definition is large or complex enough that it is interfering with understanding the rest of the file, then perhaps it’s time to extract it to its own module! eslint: no-restricted-globals. 2.1 Use const for all of your references; avoid using var. The Airbnb style guide is identified as eslint-config-airbnb in the NPM repository. You can always transpile to your preferred module system. 2,975. 10.8 Multiline imports should be indented just like multiline array and object literals. 18.6 Use // TODO: to annotate solutions to problems. Use a leading dot, which Following this style guide will ensure your code has a level of clarity that makes reading and maintaining your code easier for anyone who has to work on it. Regardless of your intentions, adding underscore prefixes to your properties does not actually make them private, and any property (underscore-prefixed or not) should be treated as being public. Decluttering is the key. Inconsistencies between keyboard shortcuts and keyboard commands used by people using screenreaders and keyboards complicate accessibility. Avoid manipulating prototype directly. This is helpful when later on you might need to assign a variable depending on one of the previously assigned variables. 2.3 Note that both let and const are block-scoped. eslint: no-underscore-dangle. eslint: import/first. eslint: object-curly-spacing, 19.13 Avoid having lines of code that are longer than 100 characters (including whitespace). eslint: prefer-const, no-const-assign. This differs from ECMAScript 3, which merely discouraged (but allowed) octal interpretation. 29.2 Use Number.isFinite instead of global isFinite. Why? To encourage more files that only ever export one thing, which is better for readability and maintainability. The global isFinite coerces non-numbers to numbers, returning true for anything that coerces to a finite number. eslint: space-before-blocks, 19.3 Place 1 space before the opening parenthesis in control statements (if, while etc.). Reassigning parameters can lead to unexpected behavior, especially when accessing the arguments object. Note that in a world with modules everywhere, you almost never need an IIFE. Varying this API for a subset of your app makes the code less readable and less maintainable, and may cause bugs. eslint: eol-last, 19.6 Use indentation when making long method chains (more than 2 method chains). Although the one-liner is concise, having one clear way to import and one clear way to export makes things consistent. eslint: wrap-iife. Numbers are represented as 64-bit values, but bitshift operations always return a 32-bit integer (source). When you stop to think about how Batman had anything to do ', 'This is a super long error that was thrown because of Batman. 694. We recommend enclosing / and * in parentheses because their precedence can be ambiguous when they are mixed. An immediately invoked function expression is a single unit - wrapping both it, and its invocation parens, in parens, cleanly expresses this. It can also cause optimization issues, especially in V8. ESLint is a program that identifies… SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. It’s easier to tell which properties are using the shorthand. Why? HOCs that proxy down props and hoist propTypes. Do not use underscore prefix for internal methods of a React component. eslint: implicit-arrow-linebreak. Including extensions inhibits refactoring, and inappropriately hardcodes implementation details of the module you're importing in every consumer. Why? EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 14.1 var declarations get hoisted to the top of their closest enclosing function scope, their assignment does not. Use map() / every() / filter() / find() / findIndex() / reduce() / some() / ... to iterate over arrays, and Object.keys() / Object.values() / Object.entries() to produce arrays so you can iterate over objects. 17.2 Don't use selection operators in place of control statements. The Standard Library If the image is presentational, alt can be an empty string or the must have role="presentation". eslint: react/jsx-no-bind. 12.2 Use bracket notation [] when accessing properties with a variable. To keep the approach unified, put these fallbacks in the theme. ESLint + AirBnB. This also improves readability by making it easier to visually follow complex logic. Component Naming: Use the filename as the component name. You can add new properties over time or change the order of things without breaking call sites. Destructuring objects also provides a single site of definition of the object structure that is used in the block, rather than requiring reading the entire block to determine what is used. let, const, function, and class). // cache the lookup once, in module scope. Do not use displayName for naming components. 23.9 Acronyms and initialisms should always be all uppercased, or all lowercased. A mostly reasonable approach to React and JSX. An example rule could be “avoid using console.log()“ Luckily Airbnb has written a Style Guide for JavaScript which covers most of the best practices they use. eslint: no-unused-vars. Why? This rule also enforces consistent spacing inside a close block token and previous token on the same line. Airbnb JavaScript Style Guide A mostly reasonable approach to JavaScript View on GitHub Airbnb CSS-in-JavaScript Style Guide. See issues #1024, and #490 for a more in-depth discussion. Why? RxGroups Easily group RxJava Observables together and tie them to your Android Activity lifecycle. This guide is available in other languages too. Your filename should be identical to your function’s name. A mostly reasonable approach to JavaScript. Prefer using the loader syntax in webpack.config.js. Screenreaders already announce img elements as images, so there is no need to include this information in the alt text. 12.1 Use dot notation when accessing properties. We open sourced our style guide so other teams could fork it and turn it into a Monet style guide or a Banksy style guide. Broken strings are painful to work with and make code less searchable. Eslint is a linting utility for JavaScript and JSX, with some nice rules and plugins. It became clear that eslint: arrow-parens. // Write-only variables are not considered as used. eslint: function-paren-newline, 8.1 When you must use an anonymous function (as when passing an inline callback), use arrow function notation. Why? 15.2 Conditional statements such as the if statement evaluate their expression using coercion with the ToBoolean abstract method and always follow these simple rules: 15.3 Use shortcuts for booleans, but explicit comparisons for strings and numbers. This is where Airbnb’s neighborhood guide comes in! In general we consider it subjectively easier to read. Why? eslint: import/extensions. Hire Me. Why? Why? When JavaScript encounters a line break without a semicolon, it uses a set of rules called Automatic Semicolon Insertion to determine whether or not it should regard that line break as the end of a statement, and (as the name implies) place a semicolon into your code before the line break if it thinks so. Don’t forget to explicitly name the expression, regardless of whether or not the name is inferred from the containing variable (which is often the case in modern browsers or when using compilers such as Babel). Why? eslint: class-methods-use-this. 6.3 When programmatically building up strings, use template strings instead of concatenation. eslint: func-call-spacing, 19.18 Enforce spacing between keys and values in object literal properties. This style guide is also available in other languages: Permission is hereby granted, free of charge, to any person obtaining // be what you want but it can introduce subtle bugs. eslint: no-var. Why? Keep discussions on diffs focused on the code's logic rather than its style. Why? You can also step through each declaration with the debugger, instead of jumping through all of them at once. eslint: react/jsx-boolean-value, Always include an alt prop on tags. Per the eslint documentation, unary increment and decrement statements are subject to automatic semicolon insertion and can cause silent errors with incrementing or decrementing values within an application. eslint: import/prefer-default-export. eslint: no-multi-assign. Why? Bitshift can lead to unexpected behavior for integer values larger than 32 bits. Notice how you can't even see the full bed! Use Git or checkout with SVN using the web URL. This style guide is mostly based on the standards that are currently prevalent in JavaScript, although some conventions (i.e async/await or static class fields) may still be included or prohibited on a case-by-case basis. eslint: key-spacing, 19.20 Avoid multiple empty lines, only allow one newline at the end of files, and avoid a newline at the beginning of files. For example, ReservationCard.jsx should have a reference name of ReservationCard. If nothing happens, download the GitHub extension for Visual Studio and try again. isMounted is an anti-pattern, is not available when using ES6 classes, and is on its way to being officially deprecated. They allow you to define all the properties of an object in one place. eslint: keyword-spacing, 19.4 Set off operators with spaces. We encourage you to fork this guide and change the rules to fit your team’s style guide. Make it easier to read and begin understanding unfamiliar code. Note: per above, long strings are exempt from this rule, and should not be broken up. The point of the style guide, is that no matter what you do in a big enough team, people are going to have dissenting opinions. Linebreaks surrounding = can obfuscate the value of an assignment. Why? Why? Airbnb maintains a very popular JavaScript Style Guide that is used by many JavaScript developers worldwide. let and const are block scoped and not function scoped. eslint no-plusplus. It also assumes you are installing shims/polyfills in your app, with airbnb-browser-shims or the equivalent. eslint operator-linebreak. 7.14 Prefer the use of the spread operator ... to call variadic functions. 6.1 Use single quotes '' for strings. eslint: no-duplicate-imports. 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