michael@0: function bytecode(f) {
michael@0:     if (typeof disassemble !== "function")
michael@0:         return "unavailable";
michael@0:     var d = disassemble(f);
michael@0:     return d.slice(d.indexOf("main:"), d.indexOf("\n\n"));
michael@0: }
michael@0: assertEq(bytecode(() => "hello" + "world"),
michael@0:          bytecode(() => "helloworld"));
michael@0: assertEq(bytecode(() => 2 + "2" + "2"),
michael@0:          bytecode(() => "222"));
michael@0: assertEq(bytecode(() => "x" + "3"),
michael@0:          bytecode(() => "x3"));
michael@0: 
michael@0: var s = "hoge";
michael@0: assertEq(bytecode(() => "fo" + "o" + s + "ba" + "r"),
michael@0:          bytecode(() => "foo" + s + "bar"));
michael@0: assertEq(bytecode(() => "fo" + "o" + 1 + s + 1 + "ba" + "r"),
michael@0:          bytecode(() => "foo1" + s + "1bar"));
michael@0: assertEq(bytecode(() => 1 + (2 * 2) + "x"),
michael@0:          bytecode(() => 5 + "x"));
michael@0: assertEq(s + 1 + 2, "hoge12");
michael@0: assertEq((() => s + 1 + 2)(), "hoge12");
michael@0: 
michael@0: // SpiderMonkey knows that 1 + 1 == "11".
michael@0: assertEq(bytecode(() => "x" + s + 1 + 1),
michael@0:          bytecode(() => "x" + s + "11"));
michael@0: 
michael@0: var n = 5;
michael@0: assertEq(1 + n + 1 + "ba" + "r", "7bar");
michael@0: assertEq(1 + 2 + {valueOf: () => 3, toString: () => 'x'} + 4 + 5,15);
michael@0: assertEq(1+2+n,8);
michael@0: assertEq(bytecode(() => 1 + 2 + n + 1 + 2),
michael@0:          bytecode(() => 3 + n + 1 + 2));
michael@0: assertEq(1 + 2 + n + 1 + 2, 11);
michael@0: assertEq(bytecode(() => 1 + 2 + s + 1 + 2),
michael@0:          bytecode(() => 3 + s + 1 + 2));
michael@0: assertEq(1 + 2 + s + 1 + 2, "3hoge12");
michael@0: 
michael@0: assertEq(bytecode(() => ["a" + "b" + n]),
michael@0:          bytecode(() => ["ab" + n]));
michael@0: var a = ["a" + "b" + n];
michael@0: assertEq(a[0], "ab5");
michael@0: