useRef
/*
A common use case is to access a child imperatively:
*/
function TextInputWithFocusButton() {
const inputEl = useRef(null);
const onButtonClick = () => {
// `current` points to the mounted text input element
inputEl.current.focus();
};
return (
<>
<input ref={inputEl} type="text" />
<button onClick={onButtonClick}>Focus the input</button>
</>
);
}react useEffect
import React, { useEffect } from 'react';
export const App: React.FC = () => {
useEffect(() => {
}, [/*Here can enter some value to call again the content inside useEffect*/])
return (
<div>Use Effect!</div>
);
}componentwillunmount hooks
useEffect(() => {
window.addEventListener('mousemove', () => {});
// returned function will be called on component unmount
return () => {
window.removeEventListener('mousemove', () => {})
}
}, [])react useeffect common dependency
import React, { useState, useRef, useEffect } from "react";
function EffectsDemoNoDependency() {
const [title, setTitle] = useState("default title");
const titleRef = useRef();
useEffect(() => {
console.log("useEffect");
document.title = title;
});
const handleClick = () => setTitle(titleRef.current.value);
console.log("render");
return (
<div>
<input ref={titleRef} />
<button onClick={handleClick}>change title</button>
</div>
);
}Copyright © 2021 Codeinu
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