immutableJS-updateIn方法无法按预期工作

Question

I have a map like this structure in immutable js:

myMap = {
    a: {
        b: {
            c: [
                { d: "something1", ... },
                { d: "something2", ... }
            ],
            ...
        },
        ...
    },
    ...
}

Then I want to update the value of d s.

I've tried like:

myMap.updateIn(["a", "b", "c"], (each) => {
    each.set("d", "something else");
});

and like:

myMap.updateIn(["a", "b", "c"], (each) => {
    each.map((e) => {
        e.set("d", "something else");
    });
});

But as you know, those does not work.

How can I update the value of d s?

Answer 1

I've found the reason why my code above doesn't work.

Firstly, the second code is partially correct, but first one is wrong.

The partially means that the logic was correct, but the grammar of ES6 was not.

So, the correct code is:

const updatedMyMap = myMap.updateIn(["a", "b", "c"], each => 
    each.map(e => e.set("d", "something else"))
);

In arrow function docs ,

(param1, param2, …, paramN) => { statements }

(param1, param2, …, paramN) => expression

// equivalent to: (param1, param2, …, paramN) => { return expression; }

this is why my code didn't work.

I should have returned the result of map() .