深度自引用对象的属性

Question

Is it possible to deeply self reference within a JS object?

I know it is possible to self reference at the same level, like so:

 var foo = { a: 'bar', b: 'baz', c: () => { return this.a + this.b; } }; console.log(foo.c()); // barbaz

I'm just curious if it would be possible to do so from deeper down...

 var foo = { a: 'bar', b: 'baz', c: { ca: 'hello', cb: () => { return this.a + this.b; } } }; console.log(foo.c.cb()); // barbaz

If not... How would one go about getting this to work?

Answer 1

One solution is to call your cb method with foo object as a context then this will refer to foo and a and b will be found, but then you should use regular function instead of arrow function.

 var foo = { a: 'bar', b: 'baz', c: { ca: 'hello', cb: function() { return this.a + this.b; } } }; console.log(foo.c.cb.call(foo));

Another solution is to turn c into getter and then you can use arrow functions as context will be context of the getter which is root object in this case.

 var foo = { a: 'bar', b: 'baz', get c() { return { ca: 'hello', cb: () => { return this.a + this.b; } } } }; console.log(foo.c.cb());

Answer 2

You would have to create a function that returns a referenced " self ".

You can apply the new properties to this by referencing the scope at the top level.

 let foo = createFoo(); let bar = Object.assign(createFoo(), { a : 'zam', b : 'zip' }); console.log(foo.c.cb()); // barbaz console.log(bar.c.cb()); // zamzip (extended foo) function createFoo() { let self = {}; // Create a new scope. return Object.assign(self, { a: 'bar', b: 'baz', c: { ca: 'hello', cb: () => self.a + self.b } }); }