Hey how are you? i'm using nextjs / styled components and i would like to change a string via props. I made a layout component with a main and it has an props to make it dinamic per page
Page 'prueba.js'
import React from 'react';
import Layout from '../components/Layout/Layout';
const prueba = () => {
const setNewBackground = 'green';
console.log(setNewBackground)
return (
<Layout setNewBackground={setNewBackground}>
<p>holaaaaa</p>
</Layout>
);
}
export default prueba;
Layout.js component
import React,{useState} from 'react';
import Main from './Main';
const Layout = props => {
const [background, setBackground] = useState('blue')
const setNewBackground = () => {
setBackground (background);
}
return (
<>
<Main newBackground={background}>
{props.children}
</Main>
</>
);
}
export default Layout;
And Main.js component
import styled from '#emotion/styled';
const Main = styled.main`
background:${props => props.newBackground};
height:100vh;
width:100%;
`;
export default Main;
I check it in console but it shows me undefined. Wheres the error :(? thanks and have a good year!
You don't need to create a state for that. You can use only the color prop you passed to the Layout.
Prueba.js
import React from 'react';
import Layout from '../components/Layout/Layout';
const prueba = () => {
return (
<Layout backgroundColor='green'>
<p>holaaaaa</p>
</Layout>
);
}
export default prueba;
Layout.js
import React,{useState} from 'react';
import Main from './Main';
const Layout = ({ backgroundColor, chidlren }) => {
return (
<Main backgroundColor={backgroundColor}>
{children}
</Main>
);
}
export default Layout;
Main.js
import styled from '#emotion/styled';
const Main = styled.main`
background:${({ backgroundColor }) => backgroundColor || 'your default color'};
height:100vh;
width:100%;
`;
export default Main;
Related
i have been trying to implement a context api solution since i want to use children states(data) in my app.js without lifting up the states. anyways i have tried to implement it a context api soloution to by doing the following :
i created a folder names context and then created Context.js
the code is as follows:
mport { createContext,useState } from "react";
export const Mycontext = createContext()
const Context = ({children}) =>{
const [post, setPost] = useState([])
return(
<Mycontext.Provider value={[post,setPost]}>
{children}
</Mycontext.Provider>
)
}
export default Context
i wrapped the index.js file with the Provider wrapper as follows:
import ReactDOM from 'react-dom/client';
import './index.css';
import App from './App';
import Context from './context/Context';
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(
<Context>
<App />
</Context>
);
my main goal for now is to use useState hook data or states so i can use them in higher up comonents , in this case i want my post.js file to change usestate data in context so i can then use that data to post something in App.js using a container component that takes value as a props
i will post the both post.js and container.js and app.js below
import React,{useContext,useState,useEffect,useRef} from 'react'
import '../HomeMainStyling/HomeStyling.css'
import Tweets from './Tweets'
import Context from '../../context/Context'
function Tweet() {
const tw = useRef('')
const {post,setPost} = useContext(Context);
useEffect(() => {
if (post.length) console.log(post);
}, [post]);
function PostNow(event){
event.preventDefault();
setPost((oldpost) => [tw.current.value,...oldpost]);
}
return (
<div className="tweetcontainer">
<textarea ref={tw} className="tweetinfo"></textarea>
<button className="postIt" onClick={PostNow}>tweet</button>
</div>
)
}
export default Tweet
//
the container is the following:
import React from 'react'
import '../HomeMainStyling/HomeStyling.css'
function Tweets({value}) {
return (
<h2>{value}</h2>
)
}
export default Tweets
App.js:
import Tweet from './Center/HomeMain/Tweet';
import Tweets from './Center/HomeMain/Tweets';
import { useContext,useState } from 'react';
import Context from './context/Context';
function App() {
const {post,setPost} = useContext(Context);
return (
<div className="App">
<Tweet/>
<Tweets value={post}/>
</div>
);
}
export default App;
the app should in principle post 1 h1 element for every click in Tweet components
The useContext hook takes the context you created using createContext() as a parameter, but you are passing a custom component to it, so try:
import { Mycontext } from './context/Context';
const [post, setPost] = useContext(Mycontext)
<Mycontext.Provider value={[post,setPost]}>
this is wrong you ahve to write
<Mycontext.Provider value={{post,setPost}}>
Hey Developers I am new to react js. I have made a react component named todos.js with arrow fuction in
./Components/todos.js
import React from 'react'
export const todos = () => {
return (
<div>
todos works!!!
</div>
)
}
this is how my app.js look like
import './App.css';
import Header from './Components/header';
import Footer from './Components/footer';
import { Todos } from './Components/todos';
function App() {
return (
<>
<Header></Header>
<Todos></Todos>
<Footer></Footer>
</>
);
}
export default App;
import { Todos } from './Components/todos'; I am importing the todos.js file this way. But when I import that component to my app.js it throws error saying
Attempted import error: 'Todos' is not exported from './Components/todos'.
First of all component name should be Capitalised.
Second use export default const Todos
It should be an export const Todos. The component name should be Capitalised it's a batter approach as react components.
Todos.js
import React from 'react'
export const Todos = () => {
return (
<div>
Todos works!!!
</div>
)
}
App.js
import './App.css';
import Header from './Components/Header';
import Footer from './Components/Footer';
import { Todos } from './Components/Todos';
function App() {
return (
<>
<Header />
<Todos />
<Footer />
</>
);
}
export default App;
I have a site built with React Static that has a Header component that is always present. Depending on if the current page has a hero component or not, the Header should be either light or dark.
The Header is rendered outside of the routes and the useEffect is triggered before the children is rendered. This is probably because of the routing.
This is the current code:
// App.js
import React, { useState, useEffect } from 'react'
import { Root, Routes } from 'react-static'
export default () => {
const [useDarkTheme, setUseDarkTheme] = useState(false);
useEffect(() => {
if (typeof document !== "undefined") {
const heroPresent = document.querySelectorAll(".o-hero").length > 0;
console.log("The hero is present: " + heroPresent);
setUseDarkTheme(!heroPresent);
}
})
return (
<Root>
<React.Suspense fallback={ <em>Loading...</em> }>
<Header useDarkTheme={ useDarkTheme } />
<Routes default />
</React.Suspense>
</Root>
);
}
What will be rendered at <Routes default /> is the static pages configured in React Static's static.config.js.
Below is an example of the Hero component:
// Hero.js
import React from "react";
export default () => {
console.log("This is the Hero rendering. If this exist, the Header should be dark.");
return (
<div className="o-hero">
<p>Hero!</p>
</div>
);
}
When I run the application and look at the logs this is what I get:
The hero is present: false
This is the Hero rendering. If this exist, the Header should be dark.
How could I somehow detect the presence of the Hero from the Header although the Hero is in a router and the Header is not? This feels like quite a common use case, but I could not find any info on the interwebs.
Thanks in advance!
So I ended up using useContext to provide all children with a getter and a setter for the Header's theme (dark or light). The solution is very much inspired from this answer. The solution looks like this:
// App.js
import React, { useState, useContext } from 'react'
import { Root, Routes } from 'react-static'
import { HeaderThemeContext } from "./context";
export default () => {
const { theme } = useContext(HeaderThemeContext);
const [headerTheme, setHeaderTheme] = useState(theme);
return (
<Root>
<React.Suspense fallback={ <em>Loading...</em> }>
<HeaderThemeContext.Provider value={ { theme: headerTheme, setTheme: setHeaderTheme } }>
<Header theme={ headerTheme } />
<Routes default />
</HeaderThemeContext.Provider>
</React.Suspense>
</Root>
);
}
// Hero.js
import React from "react";
import { headerThemes, setHeaderTheme } from "./context";
export default () => {
setHeaderTheme(headerThemes.DARK);
console.log("This is the Hero rendering. If this exist, the Header should be dark.");
return (
<div className="o-hero">
<p>Hero!</p>
</div>
);
}
// context.js
import React, { createContext, useContext } from "react";
export const headerThemes = {
LIGHT: "light",
DARK: "dark",
};
export const HeaderThemeContext = createContext({
theme: headerThemes.LIGHT,
setTheme: () => {}
});
// This is a hook and can only be used in a functional component with access to the HeaderThemeContext.
export const setHeaderTheme = theme => useContext(HeaderThemeContext).setTheme(theme);
This gives global access to set and get the header theme, which might not be optional, but it works for now and I think it's fine. Please let me know if there is a better way of doing this.
When attempting to pass custom props from layout to children, I am receiving the following: TypeError: props.children is not a function
Layout (functional component summary)
import React, { useState } from 'react'
import { useStaticQuery, graphql } from 'gatsby'
export default (props) => {
const {site} = useStaticQuery(
graphql`
{
site {
siteMetadata {
title
}
}
}
`
)
const globals = {title: site.siteMetadata.title}
return (
<>
{props.children({...props, ...globals})}
</>
)
}
Child (also a functional component)
import React from "react"
import Layout from '../components/layout'
export default () => {
return (
<Layout>
<main>
<h1>*site title will go here</h1>
</main>
</Layout>
)
}
Render function Pattern
To use render function pattern you need to modified your child component as
import React from "react"
import Layout from '../components/layout'
export default () => {
return (
<Layout>
{props => (<main>
<h1>{props.title}</h1>
</main>)}
</Layout>
)
}
Im studying React-Redux, Material-UI.
Now, Im trying to create Sample App, but not work.
I dont know how to improve my code.
I want to open Drawer , when Material-UI AppBar onLeftIconButtonTouchTap is clicked.
I cant bind my Action to Component, I think.
When following code is running, not fire onLeftIconButtonTouchTap event.
And when I change openDrawer to openDrawer(), JS error 'openDrawer is not a function' is found on Chrome Dev tool.
Header.jsx as a Component
import React, { PropTypes } from 'react';
import AppBar from 'material-ui/AppBar';
import Drawer from 'material-ui/Drawer';
const Header = ({
openDrawer,
open
}) => (
<div>
<AppBar
title='sample'
onLeftIconButtonTouchTap = {() => openDrawer}
/>
<Drawer
docked={false}
open={open}
/>
</div>
)
Header.PropTypes = {
openDrawer: PropTypes.func.isRequired,
open: PropTypes.bool.isRequired
}
export default Header;
HeaderContainer.jsx as a Container
import React from 'react';
import { bindActionCreators } from 'redux'
import { connect } from 'react-redux';
import { header } from '../actions'
import Header from '../components/Header';
const mapStateToProps = (state) => ({open});
const mapDispatchToProps = (dispatch) => (
{openDrawer: bindActionCreators(header, dispatch)}
);
const HeaderContainer = connect(
mapStateToProps,
mapDispatchToProps
)(Header);
export default HeaderContainer;
App.jsx as a RootComponent
import React, { Component, PropTypes } from 'react';
import Header from '../components/Header';
import injectTapEventPlugin from "react-tap-event-plugin";
import baseTheme from 'material-ui/styles/baseThemes/lightBaseTheme';
import getMuiTheme from 'material-ui/styles/getMuiTheme';
injectTapEventPlugin();
class App extends Component {
constructor(props) {
super(props);
}
getChildContext() {
return { muiTheme: getMuiTheme(baseTheme) };
}
render() {
return (
<div>
<Header />
{this.props.children}
</div>
);
}
};
App.childContextTypes = {
muiTheme: React.PropTypes.object.isRequired,
};
export default App;
Thanks in advance.
You are not binding the function correctly. You need to update your code to
<AppBar
title='sample'
onLeftIconButtonTouchTap = { openDrawer.bind(this) }
/>
More about .bind() method here: Use of the JavaScript 'bind' method