perf: remove unnecessary second filter for type narrowing (#2417)

Author: waynzh

lib/rules/enforce-style-attribute.js

@@ -92,9 +92,9 @@ module.exports = {
       return {}
     }
 
-    const topLevelElements = documentFragment.children.filter(isVElement)
-    const topLevelStyleTags = topLevelElements.filter(
-      (element) => element.rawName === 'style'
+    const topLevelStyleTags = documentFragment.children.filter(
+      /** @returns {element is VElement} */
+      (element) => isVElement(element) && element.rawName === 'style'
     )
 
     if (topLevelStyleTags.length === 0) {

lib/rules/require-explicit-slots.js

@@ -59,9 +59,10 @@ module.exports = {
     if (!documentFragment) {
       return {}
     }
-    const scripts = documentFragment.children
-      .filter(utils.isVElement)
-      .filter((element) => element.name === 'script')
+    const scripts = documentFragment.children.filter(
+      /** @returns {element is VElement} */
+      (element) => utils.isVElement(element) && element.name === 'script'
+    )
     if (scripts.every((script) => !utils.hasAttribute(script, 'lang', 'ts'))) {
       return {}
     }

lib/utils/index.js

@@ -2643,9 +2643,10 @@ function getScriptSetupElement(context) {
   if (!df) {
     return null
   }
-  const scripts = df.children
-    .filter(isVElement)
-    .filter((e) => e.name === 'script')
+  const scripts = df.children.filter(
+    /** @returns {e is VElement} */
+    (e) => isVElement(e) && e.name === 'script'
+  )
   if (scripts.length === 2) {
     return scripts.find((e) => hasAttribute(e, 'setup')) || null
   } else {

lib/utils/selector.js

@@ -580,9 +580,10 @@ function buildPseudoNthVElementMatcher(testIndex) {
  */
 function buildPseudoNthOfTypeVElementMatcher(testIndex) {
   return (element) => {
-    const elements = element.parent.children
-      .filter(isVElement)
-      .filter((e) => e.rawName === element.rawName)
+    const elements = element.parent.children.filter(
+      /** @returns {e is VElement} */
+      (e) => isVElement(e) && e.rawName === element.rawName
+    )
     return testIndex(elements.indexOf(element), elements.length)
   }
 }

lib/utils/style-variables/index.js

@@ -47,9 +47,10 @@ function getStyleVariablesContext(context) {
   if (!df) {
     return null
   }
-  const styles = df.children
-    .filter(isVElement)
-    .filter((e) => e.name === 'style')
+  const styles = df.children.filter(
+    /** @returns {e is VElement} */
+    (e) => isVElement(e) && e.name === 'style'
+  )
   if (styles.length === 0) {
     return null
   }