refactor(tracer): implement a new generic util fn to remove global ids prefix (#390)

Author: fraxken

.changeset/cool-bottles-feel.md

@@ -0,0 +1,5 @@
+---
+"@nodesecure/tracer": minor
+---
+
+Refactor global id prefix removal by implementing a new generic Util function

workspaces/tracer/src/VariableTracer.ts

@@ -16,7 +16,8 @@ import {
   notNullOrUndefined,
   isEvilIdentifierPath,
   isNeutralCallable,
-  getSubMemberExpressionSegments
+  getSubMemberExpressionSegments,
+  makePrefixRemover
 } from "./utils/index.js";
 
 // CONSTANTS
@@ -27,6 +28,7 @@ const kGlobalIdentifiersToTrace = new Set([
   "GLOBAL",
   "window"
 ]);
+const kGlobalIdentifiersRemover = makePrefixRemover(kGlobalIdentifiersToTrace);
 const kRequirePatterns = new Set([
   "require",
   "require.resolve",
@@ -136,29 +138,14 @@ export class VariableTracer extends EventEmitter {
     return this;
   }
 
-  removeGlobalIdentifier(
-    identifierOrMemberExpr: string
-  ): string {
-    if (!identifierOrMemberExpr.includes(".")) {
-      return identifierOrMemberExpr;
-    }
-
-    const globalIdentifier = [...kGlobalIdentifiersToTrace]
-      .find((globalId) => identifierOrMemberExpr.startsWith(globalId));
-
-    return globalIdentifier ?
-      identifierOrMemberExpr.slice(globalIdentifier.length + 1) :
-      identifierOrMemberExpr;
-  }
-
   getDataFromIdentifier(
     identifierOrMemberExpr: string,
     options: DataIdentifierOptions = {}
   ): null | TracedIdentifierReport {
     const { removeGlobalIdentifier = false } = options;
     if (removeGlobalIdentifier) {
       // eslint-disable-next-line no-param-reassign
-      identifierOrMemberExpr = this.removeGlobalIdentifier(identifierOrMemberExpr);
+      identifierOrMemberExpr = kGlobalIdentifiersRemover(identifierOrMemberExpr);
     }
 
     const isMemberExpr = identifierOrMemberExpr.includes(".");

workspaces/tracer/src/utils/index.ts

@@ -1,3 +1,4 @@
 export * from "./isEvilIdentifierPath.js";
 export * from "./getSubMemberExpressionSegments.js";
 export * from "./notNullOrUndefined.js";
+export * from "./makePrefixRemover.js";

workspaces/tracer/src/utils/makePrefixRemover.ts

@@ -0,0 +1,19 @@
+
+export function makePrefixRemover(
+  prefixes: Iterable<string>
+): (expr: string) => string {
+  return (
+    expr
+  ) => {
+    if (!expr.includes(".")) {
+      return expr;
+    }
+
+    const matchedPrefix = Array.from(prefixes)
+      .find((globalId) => expr.startsWith(globalId));
+
+    return matchedPrefix ?
+      expr.slice(matchedPrefix.length + 1) :
+      expr;
+  };
+}

workspaces/tracer/test/utils/makePrefixRemover.spec.ts

@@ -0,0 +1,46 @@
+// Import Node.js Dependencies
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+
+// Import Internal Dependencies
+import { makePrefixRemover } from "../../src/utils/index.js";
+
+describe("makePrefixRemover", () => {
+  it("returns the original string when no dot is present", () => {
+    const strip = makePrefixRemover(["window"]);
+    assert.strictEqual(strip("foo"), "foo");
+  });
+
+  it("returns the original string when the identifier is not at the start of the string", () => {
+    const strip = makePrefixRemover(["window"]);
+    assert.strictEqual(strip("foo.window"), "foo.window");
+  });
+
+  it("removes a matching prefix at the start of the expression", () => {
+    const strip = makePrefixRemover(["window", "globalThis"]);
+    assert.strictEqual(strip("window.bar"), "bar");
+    assert.strictEqual(strip("globalThis.console"), "console");
+  });
+
+  it("returns the original string when no prefix matches", () => {
+    const strip = makePrefixRemover(["window"]);
+    assert.strictEqual(strip("document.title"), "document.title");
+  });
+
+  it("handles nested member expressions", () => {
+    const strip = makePrefixRemover(["window"]);
+    assert.strictEqual(strip("window.document.title"), "document.title");
+  });
+
+  it("accepts any iterable of prefixes", () => {
+    const strip = makePrefixRemover(new Set(["window"]));
+    assert.strictEqual(strip("window.location"), "location");
+  });
+
+  it("uses the first matching prefix based on input order", () => {
+    const strip1 = makePrefixRemover(["window.document", "window"]);
+    assert.strictEqual(strip1("window.document.title"), "title");
+    const strip2 = makePrefixRemover(["window", "window.document"]);
+    assert.strictEqual(strip2("window.document.title"), "document.title");
+  });
+});