[Webkit-unassigned] [Bug 143247] New: Object.preventExtensions makes code much slower

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=143247

            Bug ID: 143247
           Summary: Object.preventExtensions makes code much slower
    Classification: Unclassified
           Product: WebKit
           Version: 528+ (Nightly build)
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: JavaScriptCore
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: esprehn at chromium.org

If you have

class Foo {
  constructor() {
    this.property = 1;
    Object.preventExtensions(this);
  }
}

calling new Foo() seems to be 2-3x slower than doing so without the call to preventExtensions. This is not the case in v8 or Firefox. This pattern is really nice since it catches bad assignments and typos in code.

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