util: highlight stack frames

Using `util.inspect` on errors is going to highlight userland and
node_module stack frames from now on. This is done by marking Node.js
core frames grey and frames that contain `node_modules` in their path
yellow.

That way it's easy to grasp what frames belong to what code.

PR-URL: https://github.com/nodejs/node/pull/27052
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 35 insertions, 2 deletions

diff --git a/lib/internal/util/inspect.js b/lib/internal/util/inspect.js
index a31ee5b8eb..08f627db88 100644
--- a/lib/internal/util/inspect.js
+++ b/lib/internal/util/inspect.js
@@ -86,6 +86,8 @@ const {
 
 const assert = require('internal/assert');
 
+const { NativeModule } = require('internal/bootstrap/loaders');
+
 let hexSlice;
 
 const inspectDefaultOptions = Object.seal({
@@ -115,6 +117,9 @@ const strEscapeSequencesReplacerSingle = /[\x00-\x1f\x5c]/g;
 const keyStrRegExp = /^[a-zA-Z_][a-zA-Z_0-9]*$/;
 const numberRegExp = /^(0|[1-9][0-9]*)$/;
 
+const coreModuleRegExp = /^    at (?:[^/\\(]+ \(|)((?<![/\\]).+)\.js:\d+:\d+\)?$/;
+const nodeModulesRegExp = /[/\\]node_modules[/\\](.+?)(?=[/\\])/g;
+
 const readableRegExps = {};
 
 const kMinLineLength = 16;
@@ -253,7 +258,8 @@ inspect.styles = Object.assign(Object.create(null), {
   symbol: 'green',
   date: 'magenta',
   // "name": intentionally not styling
-  regexp: 'red'
+  regexp: 'red',
+  module: 'underline'
 });
 
 function addQuotes(str, quotes) {
@@ -838,10 +844,37 @@ function formatError(err, constructor, tag, ctx) {
       }
     }
   }
+  // Ignore the error message if it's contained in the stack.
+  let pos = err.message && stack.indexOf(err.message) || -1;
+  if (pos !== -1)
+    pos += err.message.length;
   // Wrap the error in brackets in case it has no stack trace.
-  const stackStart = stack.indexOf('\n    at');
+  const stackStart = stack.indexOf('\n    at', pos);
   if (stackStart === -1) {
     stack = `[${stack}]`;
+  } else if (ctx.colors) {
+    // Highlight userland code and node modules.
+    let newStack = stack.slice(0, stackStart);
+    const lines = stack.slice(stackStart + 1).split('\n');
+    for (const line of lines) {
+      const core = line.match(coreModuleRegExp);
+      if (core !== null && NativeModule.exists(core[1])) {
+        newStack += `\n${ctx.stylize(line, 'undefined')}`;
+      } else {
+        // This adds underscores to all node_modules to quickly identify them.
+        let nodeModule;
+        newStack += '\n';
+        let pos = 0;
+        while (nodeModule = nodeModulesRegExp.exec(line)) {
+          // '/node_modules/'.length === 14
+          newStack += line.slice(pos, nodeModule.index + 14);
+          newStack += ctx.stylize(nodeModule[1], 'module');
+          pos = nodeModule.index + nodeModule[0].length;
+        }
+        newStack += pos === 0 ? line : line.slice(pos);
+      }
+    }
+    stack = newStack;
   }
   // The message and the stack have to be indented as well!
   if (ctx.indentationLvl !== 0) {