Бесконечный эффект типирования реагирует
const { render } = ReactDOM;
const { useState, useEffect } = React;
const CONSTANTS = {
DELETING_SPEED: 30,
TYPING_SPEED: 150,
}
function TypeWriter({ messages, heading }) {
const [state, setState] = useState({
text: "",
message: "",
isDeleting: false,
loopNum: 0,
typingSpeed: CONSTANTS.TYPING_SPEED,
});
useEffect(() => {
let timer = "";
const handleType = () => {
setState(cs => ({
...cs, // cs means currentState
text: getCurrentText(cs),
typingSpeed: getTypingSpeed(cs)
}));
timer = setTimeout(handleType, state.typingSpeed);
};
handleType();
return () => clearTimeout(timer);
}, [state.isDeleting]);
useEffect(() => {
if (!state.isDeleting && state.text === state.message) {
setTimeout(() => {
setState(cs => ({
...cs,
isDeleting: true
}))
}, 500);
} else if (state.isDeleting && state.text === "") {
setState(cs => ({
...cs, // cs means currentState
isDeleting: false,
loopNum: cs.loopNum + 1,
message: getMessage(cs, messages)
}));
}
}, [state.text, state.message, state.isDeleting, messages]);
function getCurrentText(currentState) {
return currentState.isDeleting
? currentState.message.substring(0, currentState.text.length - 1)
: currentState.message.substring(0, currentState.text.length + 1);
}
function getMessage(currentState, data) {
return data[Number(currentState.loopNum) % Number(data.length)];
}
function getTypingSpeed(currentState) {
return currentState.isDeleting
? CONSTANTS.TYPING_SPEED
: CONSTANTS.DELETING_SPEED;
}
return (
<h1>
{heading}
<span>{state.text}</span>
<span id="cursor" />
</h1>
);
}
let msgs = ["WELCOME TO MY WORLD","THIS IS MY WEBSITE","I AM AT YOUR SERVICE"];
render(<TypeWriter heading={"Things I want to type:"} messages={msgs} />, document.body);
Wicked Wombat
