72 lines
2.2 KiB
JavaScript
72 lines
2.2 KiB
JavaScript
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describe("named function expression scoping", () => {
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test("name is visible inside function body", () => {
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const f = function factorial(n) {
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if (n <= 1) return 1;
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return n * factorial(n - 1);
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};
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expect(f(5)).toBe(120);
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});
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test("name is not visible outside function body", () => {
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const f = function inner() {
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return 42;
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};
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expect(() => inner).toThrowWithMessage(ReferenceError, "'inner' is not defined");
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});
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test("name binding is immutable inside function", () => {
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const f = function immutableName() {
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immutableName = "changed";
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return typeof immutableName;
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};
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expect(f()).toBe("function");
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});
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test("outer variable with same name is shadowed inside", () => {
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let shadow = "outer";
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const f = function shadow() {
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return typeof shadow;
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};
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expect(shadow).toBe("outer");
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expect(f()).toBe("function");
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});
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test("assignment to outer variable with same name works", () => {
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let outer;
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outer = function outer() {
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return outer.name;
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};
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expect(outer()).toBe("outer");
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expect(typeof outer).toBe("function");
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});
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test("property access on outer variable with same name works", () => {
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let Foo;
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Foo = function Foo() {};
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Foo.bar = 42;
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expect(Foo.bar).toBe(42);
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});
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test("nested named function expressions", () => {
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const outer = function outerFn() {
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const inner = function innerFn() {
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return typeof outerFn + "," + typeof innerFn;
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};
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return inner();
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};
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expect(outer()).toBe("function,function");
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});
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test("same name in nested function expressions", () => {
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const outer = function sameName() {
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const inner = function sameName() {
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return sameName.length;
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};
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return [sameName.length, inner()];
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};
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const result = outer();
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expect(result[0]).toBe(0); // outer sameName
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expect(result[1]).toBe(0); // inner sameName (shadows outer)
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});
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});
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