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React hooks todo example
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import React, { useState, useContext } from 'react'; | |
const DataContext = React.createContext(); | |
const DataProvider = (props) => { | |
const [items, setItems] = useState([ | |
"Thing 1", | |
"Thing 2", | |
"Thing 3", | |
]); | |
function addItem(item) { | |
setItems( | |
items.concat(item) | |
); | |
} | |
function deleteItem(index) { | |
setItems( | |
items.filter((item, i) => i !== index) | |
); | |
} | |
return ( | |
<DataContext.Provider value={{ | |
items, | |
setItems, | |
addItem, | |
deleteItem, | |
}}> | |
{props.children} | |
</DataContext.Provider> | |
); | |
}; | |
const Main = () => ( | |
<div> | |
<TodoList /> | |
<NewTodo /> | |
</div> | |
); | |
const TodoList = () => { | |
const data = useContext(DataContext); | |
return ( | |
<ul> | |
{data.items && data.items.map((item, index) => | |
<li key={item}> | |
{item} | |
<button onClick={() => data.deleteItem(index)}>Delete</button> | |
</li> | |
)} | |
</ul> | |
); | |
}; | |
const useInputState = (initialValue) => { | |
const [value, setValue] = useState(initialValue); | |
return { | |
value, | |
onChange: e => { | |
setValue(e.target.value); | |
}, | |
reset: () => setValue(""), | |
}; | |
}; | |
const NewTodo = () => { | |
const data = useContext(DataContext); | |
const todo = useInputState(""); | |
return ( | |
<form onSubmit={e => { | |
e.preventDefault(); | |
data.addItem(todo.value); | |
todo.reset(); | |
}}> | |
<input | |
name="todo" | |
type="text" | |
placeholder="New Item" | |
onChange={todo.onChange} | |
value={todo.value} | |
/> | |
</form> | |
); | |
}; | |
class App extends React.Component { | |
render() { | |
return ( | |
<DataProvider> | |
<h1>React Hooks Example</h1> | |
<Main /> | |
</DataProvider> | |
); | |
} | |
} | |
export default App; |
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