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    1.7.0 • Public • Published

    Optional chaining codemod

    Build Status npm version PRs Welcome

    This is a codemod to migrate different types of lodash get calls and a && a.b kind of expressions to use optional chaining and nullish coalescing instead.

    Following babel plugins are required to transpile optional chaining and nullish coalescing:

    What it does?

    • a && a.b becomes a?.b
    • _.get(foo, 'a.b') and _.get(foo, ['a', 'b']) becomes foo?.a?.b
    • _.get(foo, 'a.b', defaultValue) becomes foo?.a?.b ?? defaultValue

    You can check out the __textfixtures__ folder to see full list of supported transformations.

    Why should I migrate to use optional chaining?

    • When using static type checkers like Flow or Typescript, optional chaining provides much better type safety than lodash get. Optional chaining is standard Javascript feature.
    • It also has a neater syntax than chaining && expressions one after another.


    $ yarn global add optional-chaining-codemod


    $ npm install -g optional-chaining-codemod


    $ optional-chaining-codemod ./**/*.js --ignore-pattern="**/node_modules/**"

    with flow parser:

    $ optional-chaining-codemod ./**/*.js --ignore-pattern="**/node_modules/**" --parser=flow

    with typescript parser:

    $ optional-chaining-codemod ./**/*.ts --ignore-pattern="**/node_modules/**" --parser=ts

    with typescript+react parser:

    $ optional-chaining-codemod ./**/*.tsx --parser=tsx

    The CLI is the same as in jscodeshift except you can omit the transform file.

    Alternatively, you can run the codemod using jscodeshift as follows:

    $ yarn global add jscodeshift
    $ yarn add optional-chaining-codemod
    $ jscodeshift -t node_modules/optional-chaining-codemod/transform.js --ignore-pattern="**/node_modules/**" ./**/*.js


    This codemod has two flags:

    1. --skipVariables to skip variables passed to lodash get
    2. --skipTemplateStrings to skip template strings passed to lodash get

    Especially the first case is risky as the variable might actually be something like var bar = "a.b.c" and produce from _.get(foo, bar) following: foo?[bar] although lodash would treat it like foo?.a?.b?.c".


    Contributions are more than welcome! One area of improvement could be e.g better CLI or finding out new areas to migrate to use optional chaining.


    npm i optional-chaining-codemod

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    • villesau