perf: reduce array iterations (#886)

9romise · web-flow · commit 84b7d0e2c91f · 2025-07-17T00:50:29.000Z
diff --git a/packages/eslint-plugin/rules/array-element-newline/array-element-newline.ts b/packages/eslint-plugin/rules/array-element-newline/array-element-newline.ts
@@ -224,9 +224,7 @@ export default createRule<RuleOptions, MessageIds>({
        * ]
        */
       if (options.multiline) {
-        elementBreak = elements
-          .filter(element => element !== null)
-          .some(element => !isSingleLine(element))
+        elementBreak = elements.some(element => element !== null && !isSingleLine(element))
       }
 
       let linebreaksCount = 0
diff --git a/packages/eslint-plugin/rules/line-comment-position/line-comment-position.ts b/packages/eslint-plugin/rules/line-comment-position/line-comment-position.ts
@@ -89,7 +89,10 @@ export default createRule<RuleOptions, MessageIds>({
       Program() {
         const comments = sourceCode.getAllComments()
 
-        comments.filter(token => token.type === 'Line').forEach((node) => {
+        comments.forEach((node) => {
+          if (node.type !== 'Line')
+            return
+
           if (applyDefaultIgnorePatterns && (defaultIgnoreRegExp.test(node.value) || fallThroughRegExp.test(node.value)))
             return
 
diff --git a/packages/eslint-plugin/rules/lines-around-comment/lines-around-comment.ts b/packages/eslint-plugin/rules/lines-around-comment/lines-around-comment.ts
@@ -7,13 +7,12 @@ import { createRule } from '#utils/create-rule'
  * @returns an array with with any line numbers that are empty.
  */
 function getEmptyLineNums(lines: string[]): number[] {
-  const emptyLines = lines
-    .map((line, i) => ({
-      code: line.trim(),
-      num: i + 1,
-    }))
-    .filter(line => !line.code)
-    .map(line => line.num)
+  const emptyLines: number[] = []
+
+  lines.forEach((line, i) => {
+    if (!line.trim())
+      emptyLines.push(i + 1)
+  })
 
   return emptyLines
 }
diff --git a/packages/eslint-plugin/rules/multiline-comment-style/multiline-comment-style.ts b/packages/eslint-plugin/rules/multiline-comment-style/multiline-comment-style.ts
@@ -475,8 +475,14 @@ export default createRule<RuleOptions, MessageIds>({
 
             return commentGroups
           }, [])
-          .filter(commentGroup => !(commentGroup.length === 1 && isSingleLine(commentGroup[0])))
-          .forEach(commentGroupCheckers[option])
+          .forEach((commentGroup) => {
+            if (commentGroup.length === 1 && isSingleLine(commentGroup[0]))
+              return
+
+            const check = commentGroupCheckers[option]
+
+            check(commentGroup)
+          })
       },
     }
   },
diff --git a/packages/eslint-plugin/rules/no-extra-parens/no-extra-parens.ts b/packages/eslint-plugin/rules/no-extra-parens/no-extra-parens.ts
@@ -796,9 +796,10 @@ export default createRule<RuleOptions, MessageIds>({
             report(node.callee)
           }
         }
-        node.arguments
-          .filter(arg => hasExcessParensWithPrecedence(arg, PRECEDENCE_OF_ASSIGNMENT_EXPR))
-          .forEach(report)
+        node.arguments.forEach((arg) => {
+          if (hasExcessParensWithPrecedence(arg, PRECEDENCE_OF_ASSIGNMENT_EXPR))
+            report(arg)
+        })
       }
 
       if (isTypeAssertion(node.callee)) {
@@ -924,13 +925,16 @@ export default createRule<RuleOptions, MessageIds>({
               ? { ...element, type: AST_NODE_TYPES.FunctionExpression as any }
               : element,
           )
-          .filter((e): e is NonNullable<typeof e> => !!e && hasExcessParensWithPrecedence(e, PRECEDENCE_OF_ASSIGNMENT_EXPR))
-          .forEach(report)
+          .forEach((ele) => {
+            if (!!ele && hasExcessParensWithPrecedence(ele, PRECEDENCE_OF_ASSIGNMENT_EXPR))
+              report(ele)
+          })
       },
       ArrayPattern(node) {
-        node.elements
-          .filter((e): e is NonNullable<typeof e> => !!e && canBeAssignmentTarget(e) && hasExcessParens(e))
-          .forEach(report)
+        node.elements.forEach((ele) => {
+          if (!!ele && canBeAssignmentTarget(ele) && hasExcessParens(ele))
+            report(ele)
+        })
       },
       ArrowFunctionExpression(node) {
         if (isTypeAssertion(node.body))
@@ -1326,18 +1330,26 @@ export default createRule<RuleOptions, MessageIds>({
       },
       'NewExpression': checkCallNew,
       ObjectExpression(node) {
-        node.properties
-          .filter((property): property is Tree.Property => property.type === 'Property' && property.value && hasExcessParensWithPrecedence(property.value, PRECEDENCE_OF_ASSIGNMENT_EXPR))
-          .forEach(property => report(property.value))
+        node.properties.forEach((property) => {
+          if (
+            property.type === 'Property'
+            && property.value
+            && hasExcessParensWithPrecedence(property.value, PRECEDENCE_OF_ASSIGNMENT_EXPR)
+          ) {
+            report(property.value)
+          }
+        })
       },
       ObjectPattern(node) {
-        node.properties
-          .filter((property) => {
-            const value = property.value
-
-            return value && canBeAssignmentTarget(value) && hasExcessParens(value)
-          })
-          .forEach(property => report(property.value!))
+        node.properties.forEach(({ value }) => {
+          if (
+            value
+            && canBeAssignmentTarget(value)
+            && hasExcessParens(value)
+          ) {
+            report(value)
+          }
+        })
       },
       Property(node) {
         if (node.computed) {
@@ -1374,9 +1386,10 @@ export default createRule<RuleOptions, MessageIds>({
       SequenceExpression(node) {
         const precedenceOfNode = precedence(node)
 
-        node.expressions
-          .filter(e => hasExcessParensWithPrecedence(e, precedenceOfNode))
-          .forEach(report)
+        node.expressions.forEach((expression) => {
+          if (hasExcessParensWithPrecedence(expression, precedenceOfNode))
+            report(expression)
+        })
       },
       SpreadElement(node) {
         if (isTypeAssertion(node.argument))
@@ -1399,9 +1412,10 @@ export default createRule<RuleOptions, MessageIds>({
           report(node.discriminant)
       },
       TemplateLiteral(node) {
-        node.expressions
-          .filter(e => e && hasExcessParens(e))
-          .forEach(report)
+        node.expressions.forEach((expression) => {
+          if (hasExcessParens(expression))
+            report(expression)
+        })
       },
       ThrowStatement(node) {
         if (!node.argument || isTypeAssertion(node.argument))
diff --git a/packages/eslint-plugin/rules/spaced-comment/spaced-comment.ts b/packages/eslint-plugin/rules/spaced-comment/spaced-comment.ts
@@ -371,7 +371,11 @@ export default createRule<RuleOptions, MessageIds>({
       Program() {
         const comments = sourceCode.getAllComments()
 
-        comments.filter(token => !isHashbangComment(token)).forEach(checkCommentForSpace)
+        comments.forEach((comment) => {
+          if (!isHashbangComment(comment))
+            checkCommentForSpace(comment)
+        },
+        )
       },
     }
   },
