this.eventSource = new EventSource("http://localhost:5000/api/......")
componentDidMount() {
......
this.subscribeToServerEvent()
}
subscribeToServerEvent = () => {
this.eventSource.onmessage = e => {
try {
......
this.setState({ ..... })
} catch (e) {
console.log('error parsing server response', e)
}
}
}
const obj = data.reduce((prev, item) => {
prev[item.id] = (({id, test}) => ({id, test}))(item); // копируем выбранные свойства
if (!item.hasOwnProperty('test')) delete prev[item.id].test; // удаляем пустышку, если нет ее
return prev;
}, {});
data.map(item => obj[item.id] = item.test ? {
id: item.id,
test: item.test
} : {
id: item.id
})
const removeFromCart = productId => ({
type: types.REMOVE_FROM_CART,
productId
})
<div class="spinner"><div>.spinner {
color: black;
font-size: 5rem;
}
.spinner::before {
display: inline-block;
text-align: center;
font-family: monospace;
width: 5rem;
content: "";
animation: spinner .8s infinite steps(4);
}
@keyframes spinner {
0%, 100% { content: "\2014"; }
25% { content: "\\"; }
50% { content: "|"; }
75% { content: "/"; }
}<div class="spinner"><div>.spinner {
color: black;
font-size: 5rem;
font-family: monospace;
}const text = [ '\u2014', '\\', '|', '/' ];
let index = -1;
setInterval(block => {
index = (index + 1) % text.length;
block.textContent = text[index];
}, 200, document.querySelector('.spinner'));