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describe("correct behavior", () => {
test("numeric indexing", () => {
const o = { 1: 23 };
expect(o[1]).toBe(23);
expect(o[1n]).toBe(23);
expect(o["1"]).toBe(23);
o[10] = "123";
expect(o[10]).toBe("123");
expect(o["10"]).toBe("123");
o[10n] = "1234";
expect(o[10]).toBe("1234");
expect(o["10"]).toBe("1234");
});
test("string indexing", () => {
let foo = "bar";
const o = {
foo,
bar: "baz",
qux: true ? 10 : 20,
hello: "friends",
};
expect(o.foo).toBe("bar");
expect(o["foo"]).toBe("bar");
expect(o.qux).toBe(10), expect(o.hello).toBe("friends");
expect(o["hello"]).toBe("friends");
});
test("symbol keys", () => {
let object = {};
let symbol = Symbol("foo");
object[symbol] = 2;
expect(object[symbol]).toBe(2);
});
test("numeric keys", () => {
const hex = { 0x10: "16" };
const oct = { 0o10: "8" };
const bin = { 0b10: "2" };
const float = { 0.5: "0.5" };
expect(hex["16"]).toBe("16");
expect(oct["8"]).toBe("8");
expect(bin["2"]).toBe("2");
expect(float["0.5"]).toBe("0.5");
});
test("computed properties", () => {
const foo = "bar";
const computed = "computed";
const o = {
[1 + 2]: 42,
[`I am a ${computed} key`]: foo,
};
expect(o[3]).toBe(42);
expect(o["I am a computed key"]).toBe("bar");
});
test("duplicate keys", () => {
const o = {
duplicate: "hello",
duplicate: "world",
};
expect(o.duplicate).toBe("world");
});
test("assigning after creation", () => {
const o = {};
o.baz = "test";
expect(o.baz).toBe("test");
expect(o["baz"]).toBe("test");
expect(o[-1]).toBeUndefined();
o[-1] = "hello friends";
expect(o[-1]).toBe("hello friends");
expect(o["-1"]).toBe("hello friends");
});
test("floating point keys", () => {
const math = { 3.14: "pi" };
expect(math["3.14"]).toBe("pi");
expect(math[3.14]).toBe("pi");
});
test("keywords as property keys", () => {
const o2 = {
return: 1,
yield: 1,
for: 1,
catch: 1,
break: 1,
};
expect(o2.return).toBe(1);
expect(o2.yield).toBe(1);
expect(o2.for).toBe(1);
expect(o2.catch).toBe(1);
expect(o2.break).toBe(1);
});
test("prototypical inheritance", () => {
var base = {
getNumber() {
return 10;
},
};
var derived = {
getNumber() {
return 20 + super.getNumber();
},
};
Object.setPrototypeOf(derived, base);
expect(derived.getNumber()).toBe(30);
});
});
describe("side effects", () => {
let a;
const append = x => {
a.push(x);
};
test("computed key side effects", () => {
a = [];
const o3 = { [append(1)]: 1, [append(2)]: 2, [append(3)]: 3 };
expect(a).toHaveLength(3);
expect(a[0]).toBe(1);
expect(a[1]).toBe(2);
expect(a[2]).toBe(3);
expect(o3.undefined).toBe(3);
});
test("value side effects", () => {
a = [];
const o4 = { test: append(1), test: append(2), test: append(3) };
expect(a).toHaveLength(3);
expect(a[0]).toBe(1);
expect(a[1]).toBe(2);
expect(a[2]).toBe(3);
expect(o4.test).toBeUndefined();
});
});
describe("shorthanded properties with special names", () => {
test("keywords cannot be used", () => {
expect("({ function, })").not.toEval();
expect("({ var, })").not.toEval();
expect("({ const, })").not.toEval();
expect("({ class, })").not.toEval();
});
test("reserved words are allowed in non-strict mode", () => {
{
var implements = 3;
expect({ implements }).toEqual({ implements: 3 });
}
{
var public = "a";
expect({ public }).toEqual({ public: "a" });
}
{
var let = 9;
expect({ let }).toEqual({ let: 9 });
}
{
var await = 8;
expect({ await }).toEqual({ await: 8 });
}
{
var async = 7;
expect({ async }).toEqual({ async: 7 });
}
{
var yield = 6;
expect({ yield }).toEqual({ yield: 6 });
}
});
test("reserved words are not allowed in strict mode", () => {
expect('"use strict"; var implements = 3; ({ implements })').not.toEval();
expect("\"use strict\"; var public = 'a'; ({ public })").not.toEval();
expect('"use strict"; var let = 9; ({ let, })').not.toEval();
expect('"use strict"; var yield = 6; ({ yield, })').not.toEval();
});
test("special non reserved words are allowed even in strict mode", () => {
expect('"use strict"; var await = 8; ({ await, })').toEval();
expect('"use strict"; var async = 7; ({ async, })').toEval();
});
});
describe("errors", () => {
test("syntax errors", () => {
expect("({ foo: function() { super.bar; } })").not.toEval();
expect("({ get ...foo })").not.toEval();
expect("({ get... foo })").not.toEval();
expect("({ get foo })").not.toEval();
expect("({ get foo: bar })").not.toEval();
expect("({ get [foo]: bar })").not.toEval();
expect("({ get ...[foo] })").not.toEval();
expect("({ get foo(bar) {} })").not.toEval();
expect("({ set foo() {} })").not.toEval();
expect("({ set foo(...bar) {} })").not.toEval();
expect("({ set foo(bar, baz) {} })").not.toEval();
expect("({ ...foo: bar })").not.toEval();
});
});
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