From 1dec296000da4913de8edec4c1c845452f6fdfef Mon Sep 17 00:00:00 2001
From: Rafael Oleza <rafeca@fb.com>
Date: Fri, 10 Nov 2017 04:40:43 -0800
Subject: [PATCH] Downgrade uglify-js from 3.1.8 to 3.1.1

Summary:
Uglify@3.1.7 is causing some perf issues (more specifically, this commit: https://github.com/mishoo/UglifyJS2/commit/5b4b07e9a7d67e593c6ae8d54dc77d174afd25ac) that are impacting TTI on RN views and increased memory usage.

More specifically, code like:

```
function nonTrivialFn(pre) {
  return pre + Math.random();
}
function hotFunctionCalledALotOfTimes(num) {
  return nonTrivialFn(num + Math.random());
}
hotFunctionCalledALotOfTimes(3);
hotFunctionCalledALotOfTimes(5);
```

in v3.1.7 gets converted to:

```
function hotFunctionCalledALotOfTimes(num){
  return function(pre) {
    return pre + Math.random();
  }(num + Math.random())
}
hotFunctionCalledALotOfTimes(3);
hotFunctionCalledALotOfTimes(5);
```

This causes a function creation each time `hotFunctionCalledALotOfTimes` is called.

By comparison, in v3.1.6, that previous code was converted to:

```
function nonTrivialFn(pre){
  return pre + Math.random()
}
function hotFunctionCalledALotOfTimes(num){
  return nonTrivialFn(num + Math.random())
}
hotFunctionCalledALotOfTimes(3);
hotFunctionCalledALotOfTimes(5);
```

Reviewed By: jeanlauliac, alexeylang

Differential Revision: D6296740

fbshipit-source-id: b3988d886e607103ec3ae6b9763b2f0411a8aa3c
---
 packages/metro-bundler/package.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/metro-bundler/package.json b/packages/metro-bundler/package.json
index 5d1938a8..b843e200 100644
--- a/packages/metro-bundler/package.json
+++ b/packages/metro-bundler/package.json
@@ -45,7 +45,7 @@
     "source-map": "^0.5.6",
     "temp": "0.8.3",
     "throat": "^4.1.0",
-    "uglify-es": "^3.1.8",
+    "uglify-es": "^3.1.0",
     "wordwrap": "^1.0.0",
     "write-file-atomic": "^1.2.0",
     "xpipe": "^1.0.5"