From 699b641b85632f9581f3638ccd8aa359dd8aa57f Mon Sep 17 00:00:00 2001
From: Charles Lyding <19598772+clydin@users.noreply.github.com>
Date: Fri, 12 Mar 2021 11:00:01 -0500
Subject: [PATCH] perf(@angular-devkit/build-angular): remove Webpack
 Stats.toJson usage in karma plugin

Webpack's `Stats.toJson` function is an expensive operation and is recommended to be avoided where possible. In the case of the karma plugin, the compilation errors can be accessed directly without the need for the function call.
---
 .../build_angular/src/webpack/plugins/karma/karma.ts     | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/packages/angular_devkit/build_angular/src/webpack/plugins/karma/karma.ts b/packages/angular_devkit/build_angular/src/webpack/plugins/karma/karma.ts
index 9adf9df0a984..1c77fab9f80c 100644
--- a/packages/angular_devkit/build_angular/src/webpack/plugins/karma/karma.ts
+++ b/packages/angular_devkit/build_angular/src/webpack/plugins/karma/karma.ts
@@ -167,7 +167,7 @@ const init: any = (config: any, emitter: any) => {
   webpackConfig.output.path = `/${KARMA_APPLICATION_PATH}/`;
   webpackConfig.output.publicPath = `/${KARMA_APPLICATION_PATH}/`;
 
-  let compiler: any;
+  let compiler;
   try {
     compiler = webpack(webpackConfig);
   } catch (e) {
@@ -200,11 +200,10 @@ const init: any = (config: any, emitter: any) => {
 
   let lastCompilationHash: string | undefined;
   const statsConfig = getWebpackStatsConfig();
-  compiler.hooks.done.tap('karma', (stats: any) => {
-    if (stats.compilation.errors.length > 0) {
-      const json = stats.toJson(config.stats);
+  compiler.hooks.done.tap('karma', (stats) => {
+    if (stats.hasErrors()) {
       // Print compilation errors.
-      logger.error(statsErrorsToString(json, statsConfig));
+      logger.error(statsErrorsToString(stats.compilation, statsConfig));
       lastCompilationHash = undefined;
       // Emit a failure build event if there are compilation errors.
       failureCb();