// The argument to Set may contain a value multiple times. Duplicates are discarded. var s = new Set(["testing", "testing", 123]); assertEq(s.size, 2); var values = [undefined, null, false, NaN, 0, -0, 6.022e23, -Infinity, "", "xyzzy", {}, Math.sin]; for (let v of values) { var a = [v, {}, {}, {}, v, {}, v, v]; s = new Set(a); assertEq(s.size, 5); assertEq(s.has(v), true); }