Fix JavaScript typo (#34921)

site/content/docs/5.1/components/placeholders.md

@@ -86,7 +86,7 @@ We apply additional styling to `.btn`s via `::before` to ensure the `height` is
 {{< /example >}}
 
 {{< callout info >}}
-The use of `aria-hidden="true"` only indicates that the element should be hidden to screen readers. The *loading* behavior of the placeholder depends on how authors will actually use the placeholder styles, how they plan to update things, etc. Some JavasSript code may be needed to *swap* the state of the placeholder and inform AT users of the update.
+The use of `aria-hidden="true"` only indicates that the element should be hidden to screen readers. The *loading* behavior of the placeholder depends on how authors will actually use the placeholder styles, how they plan to update things, etc. Some JavaScript code may be needed to *swap* the state of the placeholder and inform AT users of the update.
 {{< /callout >}}
 
 ### Width