From 48fd387779dba1e1c1f9554966000edc9d5bbaaf Mon Sep 17 00:00:00 2001
From: Daniel Tschinder <daniel@tschinder.de>
Date: Tue, 15 Jan 2019 12:56:24 -0800
Subject: [PATCH] perf: precalculate length

---
 packages/babel-parser/src/parser/lval.js     | 10 +++++++---
 packages/babel-parser/src/util/identifier.js |  2 +-
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/packages/babel-parser/src/parser/lval.js b/packages/babel-parser/src/parser/lval.js
index 76613bba31..1a9a690388 100644
--- a/packages/babel-parser/src/parser/lval.js
+++ b/packages/babel-parser/src/parser/lval.js
@@ -56,9 +56,13 @@ export default class LValParser extends NodeUtils {
 
         case "ObjectExpression":
           node.type = "ObjectPattern";
-          for (let index = 0; index < node.properties.length; index++) {
-            const prop = node.properties[index];
-            const isLast = index === node.properties.length - 1;
+          for (
+            let i = 0, length = node.properties.length, last = length - 1;
+            i < length;
+            i++
+          ) {
+            const prop = node.properties[i];
+            const isLast = i === last;
             this.toAssignableObjectExpressionProp(prop, isBinding, isLast);
           }
           break;
diff --git a/packages/babel-parser/src/util/identifier.js b/packages/babel-parser/src/util/identifier.js
index 1c50fcaf27..a312c9ac8d 100644
--- a/packages/babel-parser/src/util/identifier.js
+++ b/packages/babel-parser/src/util/identifier.js
@@ -64,7 +64,7 @@ const astralIdentifierCodes = [509,0,227,0,150,4,294,9,1368,2,2,1,6,3,41,2,5,0,1
 // rare.
 function isInAstralSet(code: number, set: $ReadOnlyArray<number>): boolean {
   let pos = 0x10000;
-  for (let i = 0; i < set.length; i += 2) {
+  for (let i = 0, length = set.length; i < length; i += 2) {
     pos += set[i];
     if (pos > code) return false;