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css/snippets/shake-invalid-input.md

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+---
+title: Shake on invalid input
+type: snippet
+tags: [animation]
+cover: perfect-timing
+dateModified: 2022-07-31T18:30:11+03:00
+---
+
+Creates a shake animation on invalid input.
+
+- Use the `pattern` attribute to define the regular expression which the input's value must match.
+- Use `@keyframes` to define a shake animation, using the `margin-left` property.
+- Use the `:invalid` pseudo-class to apply an `animation` to make the element shake.
+
+```html
+ <input type="text" placeholder="Letters only" pattern="[A-Za-z]*" />
+```
+
+```css
+@keyframes shake {
+  0% {
+    margin-left: 0rem;
+  }
+  25% {
+    margin-left: 0.5rem;
+  }
+  75% {
+    margin-left: -0.5rem;
+  }
+  100% {
+    margin-left: 0rem;
+  }
+}
+
+input:invalid {
+  animation: shake 0.2s ease-in-out 0s 2;
+  box-shadow: 0 0 0.6rem #ff0000;
+}
+```