110 lines
2.3 KiB
Markdown
110 lines
2.3 KiB
Markdown
---
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title: Closable alert
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tags: components,state,effect
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expertise: beginner
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cover: blog_images/flower-portrait-1.jpg
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firstSeen: 2019-09-17T13:19:30+03:00
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lastUpdated: 2021-01-07T23:57:13+02:00
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---
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Renders an alert component with `type` prop.
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- Use the `useState()` hook to create the `isShown` and `isLeaving` state variables and set both to `false` initially.
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- Define `timeoutId` to keep the timer instance for clearing on component unmount.
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- Use the `useEffect()` hook to update the value of `isShown` to `true` and clear the interval by using `timeoutId` when the component is unmounted.
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- Define a `closeAlert` function to set the component as removed from the DOM by displaying a fading out animation and set `isShown` to `false` via `setTimeout()`.
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```css
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@keyframes leave {
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0% { opacity: 1 }
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100% { opacity: 0 }
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}
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.alert {
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padding: 0.75rem 0.5rem;
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margin-bottom: 0.5rem;
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text-align: left;
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padding-right: 40px;
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border-radius: 4px;
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font-size: 16px;
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position: relative;
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}
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.alert.warning {
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color: #856404;
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background-color: #fff3cd;
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border-color: #ffeeba;
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}
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.alert.error {
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color: #721c24;
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background-color: #f8d7da;
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border-color: #f5c6cb;
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}
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.alert.leaving {
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animation: leave 0.5s forwards;
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}
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.alert .close {
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position: absolute;
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top: 0;
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right: 0;
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padding: 0 0.75rem;
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color: #333;
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border: 0;
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height: 100%;
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cursor: pointer;
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background: none;
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font-weight: 600;
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font-size: 16px;
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}
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.alert .close:after {
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content: 'x';
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}
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```
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```jsx
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const Alert = ({ isDefaultShown = false, timeout = 250, type, message }) => {
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const [isShown, setIsShown] = React.useState(isDefaultShown);
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const [isLeaving, setIsLeaving] = React.useState(false);
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let timeoutId = null;
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React.useEffect(() => {
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setIsShown(true);
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return () => {
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clearTimeout(timeoutId);
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};
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}, [isDefaultShown, timeout, timeoutId]);
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const closeAlert = () => {
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setIsLeaving(true);
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timeoutId = setTimeout(() => {
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setIsLeaving(false);
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setIsShown(false);
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}, timeout);
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};
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return (
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isShown && (
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<div
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className={`alert ${type} ${isLeaving ? 'leaving' : ''}`}
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role="alert"
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>
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<button className="close" onClick={closeAlert} />
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{message}
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</div>
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)
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);
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};
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```
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```jsx
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ReactDOM.render(
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<Alert type="info" message="This is info" />,
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document.getElementById('root')
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);
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```
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