src/third_party/mozjs-45/js/src/jit-test/tests/jaeger/clonefun.js

// Functions which have been marked as singletons should not be cloned.

BeatDetektor = function()
{
    this.config = BeatDetektor.config;

    assertEq(this.config.a, 0);
    assertEq(this.config.b, 1);
}

BeatDetektor.config_default = { a:0, b:1 };
BeatDetektor.config = BeatDetektor.config_default;

var bd = new BeatDetektor();

assertEq(bd.config === BeatDetektor.config, true);