如何在JavaScript中添加新项目以进行结构化？

Question

I have a struct in JavaScript

    settings = {
        "type-1": {
            "setting-1": true,
            "setting-2": 2
         }
        "type-2": {
            "setting-3": "value",
         }
    };

I can modify the items:

settings["type-1"]["setting-1"] = false;

But how can I add a new item in this struct?

Trying

settings["type-new"]["setting-100"] = "new one";

But settings["type-new"] is undefined. So how to add a new one?

Answer 1

您可以一行完成：

settings["type-new"] = {"setting-100": "new one"}

Answer 2

You need to set settings["type-new"] to an object first.

settings["type-new"] = {};
settings["type-new"]["setting-100"] = "new one";

Answer 3

Dogbert got it right, since you're using object literals (that's what they're called, not structs :P), you have to create them, before you can assign values to them. Doing settings["type-new"]["setting-100"] = "new one"; is equivalent to undefined["setting-100"] = "new one"; . That's why it doesn't work.

On the side, you're really better off not using dashes in your keys, I find it easier to write code like yours along the lines of:

settings.typeNew.setting100 = "new one";

Which is more intuitive (the [""] notation is very serviceable in cases where the property name is the value of a variable, and you -rightly so- don't want to use eval).