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Editorial Team
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Asked: 2026-05-26T10:28:11+00:00

I’ve tried to understand better why should one (or shouldn’t) inherit from Object (

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I’ve tried to understand better why should one (or shouldn’t) inherit from Object (var o = Object.create(null);). If I’ve got the answer right, performance reasons seemed to be the main viable reason to “inherit” from null.

So, I wanted to check it (utilizing small, handy and cute profiler called JSLitmus):

<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>Title</title>

    <script src="JSLitmus.js"></script>
    <script>
    JSLitmus.test('Prototypeless test', function() {
        var o1 = Object.create(null);
        o1.foo = "bar";
        for (i = 0; i < 1000000; ++i) {
          o1.foo;
        };
    });

    JSLitmus.test('Prototypeful test', function() {
        var o2 = {};
        o2.foo = "bar";
        for (i = 0; i < 1000000; ++i) {
          o2.foo;
        };
    });

    </script>

</head>
<body>
</body>
</html>

When executed, I’ve got the same (controversial) results. Does it mean that there is no performance penalty when inheriting from Object?

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1 Answer

  1. Editorial Team

    I’ve reconsidered my own code and slightly modified the code to make the foo field lookup to propagate through the “inheritance” chain:

    <html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>Title</title>

    <script src="JSLitmus.js"></script>
    <script>
    var o1 = Object.create(null);
    o1.foo = "bar";

    var o2 = Object.create(o1);

    var count;

    JSLitmus.test('Prototypeless test', function() {
        while(--count) {
          o1.foo;
        };
    });

    JSLitmus.test('Prototypeful test', function() {
        while(--count) {
          o2.foo;
        };
    });

    </script>

</head>
<body>
</body>
</html>

    In this way, I’ve got 10% better results when accessing the o1 property.

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