> For the complete documentation index, see [llms.txt](https://ploegert.gitbook.io/til/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ploegert.gitbook.io/til/programmy/react.md). # react - [A Component Is Just A Bag Of Data](https://ploegert.gitbook.io/til/programmy/react/a-component-is-just-a-bag-of-data.md) - [Access The Latest Lifecycle Methods In An Old App](https://ploegert.gitbook.io/til/programmy/react/access-the-latest-lifecycle-methods-in-an-old-app.md) - [Accessing Env Vars In create-react-app](https://ploegert.gitbook.io/til/programmy/react/accessing-env-vars-in-create-react-app.md) - [Accessing Location Within @reach/router](https://ploegert.gitbook.io/til/programmy/react/accessing-location-within-reach-router.md) - [Allow md As An Extension With gatsby-mdx](https://ploegert.gitbook.io/til/programmy/react/allow-md-as-an-extension-with-gatsby-mdx.md) - [Alter The Display Name Of A Component](https://ploegert.gitbook.io/til/programmy/react/alter-the-display-name-of-a-component.md) - [Building A React App In The Browser](https://ploegert.gitbook.io/til/programmy/react/building-a-react-app-in-the-browser.md) - [Check The Type Of A Child Component](https://ploegert.gitbook.io/til/programmy/react/check-the-type-of-a-child-component.md) - [Conditionally Including Event Handler Functions](https://ploegert.gitbook.io/til/programmy/react/conditionally-including-event-handler-functions.md) - [Create A Snowpack-Bundled React App](https://ploegert.gitbook.io/til/programmy/react/create-a-snowpack-bundled-react-app.md) - [Create Dynamically Named Custom React Components](https://ploegert.gitbook.io/til/programmy/react/create-dynamically-named-custom-react-components.md) - [create-react-app Comes With Lodash](https://ploegert.gitbook.io/til/programmy/react/create-react-app-comes-with-lodash.md) - [create-react-app Has A Default Test Setup File](https://ploegert.gitbook.io/til/programmy/react/create-react-app-has-a-default-test-setup-file.md) - [CSS !important Is Not Supported By Inline Styles](https://ploegert.gitbook.io/til/programmy/react/css-important-is-not-supported-by-inline-styles.md) - [Debug Jest Tests In create-react-app](https://ploegert.gitbook.io/til/programmy/react/debug-jest-tests-in-create-react-app.md) - [Defining State In A Simple Class Component](https://ploegert.gitbook.io/til/programmy/react/defining-state-in-a-simple-class-component.md) - [Destructure Variables As Props To A Component](https://ploegert.gitbook.io/til/programmy/react/destructure-variables-as-props-to-a-component.md) - [Details Tags Are A Controllable Component](https://ploegert.gitbook.io/til/programmy/react/details-tags-are-a-controllable-component.md) - [Dispatch Anywhere With Redux](https://ploegert.gitbook.io/til/programmy/react/dispatch-anywhere-with-redux.md) - [Dynamically Add Props To A Child Component](https://ploegert.gitbook.io/til/programmy/react/dynamically-add-props-to-a-child-component.md) - [Dynamically Create HTML Elements](https://ploegert.gitbook.io/til/programmy/react/dynamically-create-html-elements.md) - [Enforce Specific Values With PropTypes](https://ploegert.gitbook.io/til/programmy/react/enforce-specific-values-with-proptypes.md) - [Focus An Input With useRef Hook](https://ploegert.gitbook.io/til/programmy/react/focus-an-input-with-useref-hook.md) - [Force A Component To Only Have One Child](https://ploegert.gitbook.io/til/programmy/react/force-a-component-to-only-have-one-child.md) - [Forcing A Child Remount With The Key Prop](https://ploegert.gitbook.io/til/programmy/react/forcing-a-child-remount-with-the-key-prop.md) - [Formik Connected Components](https://ploegert.gitbook.io/til/programmy/react/formik-connected-components.md) - [Formik's Validation Schema As A Function](https://ploegert.gitbook.io/til/programmy/react/formiks-validation-schema-as-a-function.md) - [Inactive And Active Component Styles With Radium](https://ploegert.gitbook.io/til/programmy/react/inactive-and-active-component-styles-with-radium.md) - [Inline Style Attributes Should Be Camel Cased](https://ploegert.gitbook.io/til/programmy/react/inline-style-attributes-should-be-camel-cased.md) - [Manage State In A Functional Component](https://ploegert.gitbook.io/til/programmy/react/manage-state-in-a-functional-component.md) - [Mapping Over One Or Many Children](https://ploegert.gitbook.io/til/programmy/react/mapping-over-one-or-many-children.md) - [Mock A Function That A Component Imports](https://ploegert.gitbook.io/til/programmy/react/mock-a-function-that-a-component-imports.md) - [Navigate With State Via @reach/router](https://ploegert.gitbook.io/til/programmy/react/navigate-with-state-via-reach-router.md) - [Pairing A Callback With A useState Hook](https://ploegert.gitbook.io/til/programmy/react/pairing-a-callback-with-a-usestate-hook.md) - [Pass A Function To A useState Updater](https://ploegert.gitbook.io/til/programmy/react/pass-a-function-to-a-usestate-updater.md) - [Passing Props Down To React-Router Route](https://ploegert.gitbook.io/til/programmy/react/passing-props-down-to-react-router-route.md) - [Prevent reach/router Redirect Error Screen In Dev](https://ploegert.gitbook.io/til/programmy/react/prevent-reach-router-redirect-error-screen-in-dev.md) - [Proxy To An API Server In Development With CRA](https://ploegert.gitbook.io/til/programmy/react/proxy-to-an-api-server-in-development-with-cra.md) - [Quickly Search For A Component With React DevTools](https://ploegert.gitbook.io/til/programmy/react/quickly-search-for-a-component-with-react-devtools.md) - [@reach/router Renders To A Div](https://ploegert.gitbook.io/til/programmy/react/reach-router-renders-to-a-div.md) - [Read Only Input Elements](https://ploegert.gitbook.io/til/programmy/react/read-only-input-elements.md) - [Rendering Multiple Nodes With Fragments](https://ploegert.gitbook.io/til/programmy/react/rendering-multiple-nodes-with-fragments.md) - [Set The Type For A useState Hook](https://ploegert.gitbook.io/til/programmy/react/set-the-type-for-a-usestate-hook.md) - [Specifying Dependencies Of A useEffect Hook](https://ploegert.gitbook.io/til/programmy/react/specifying-dependencies-of-a-useeffect-hook.md) - [Spelunking Through Components With Enzyme's Dive](https://ploegert.gitbook.io/til/programmy/react/spelunking-through-components-with-enzymes-dive.md) - [Sync Your react-router State With Redux](https://ploegert.gitbook.io/til/programmy/react/sync-your-react-router-state-with-redux.md) - [Test Files In create-react-app](https://ploegert.gitbook.io/til/programmy/react/test-files-in-create-react-app.md) - [Test That Element Does Not Render In The Component](https://ploegert.gitbook.io/til/programmy/react/test-that-element-does-not-render-in-the-component.md) - [Trigger Effect Only When The Component Mounts](https://ploegert.gitbook.io/til/programmy/react/trigger-effect-only-when-the-component-mounts.md) - [Update Formik Initial Values When Props Change](https://ploegert.gitbook.io/til/programmy/react/update-formik-initial-values-when-props-change.md) - [Upgrading To The Latest React In CodeSandbox](https://ploegert.gitbook.io/til/programmy/react/upgrading-to-the-latest-react-in-codesandbox.md) - [Use A Ref To Autofocus An Input](https://ploegert.gitbook.io/til/programmy/react/use-a-ref-to-autofocus-an-input.md) - [Use React 16 With Gatsby](https://ploegert.gitbook.io/til/programmy/react/use-react-16-with-gatsby.md) - [Use withRouter To Pass Down React-Router History](https://ploegert.gitbook.io/til/programmy/react/use-withrouter-to-pass-down-react-router-history.md) - [Visually Select A React Element For Inspection](https://ploegert.gitbook.io/til/programmy/react/visually-select-a-react-element-for-inspection.md) - [Who Is Your Favorite Child?](https://ploegert.gitbook.io/til/programmy/react/who-is-your-favorite-child.md) - [Wrap The Root Of A Gatsby App In A Component](https://ploegert.gitbook.io/til/programmy/react/wrap-the-root-of-a-gatsby-app-in-a-component.md) --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://ploegert.gitbook.io/til/programmy/react.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.