如何在JavaScript对象上执行“推”操作？

Question

What I am trying to achieve is use push() on a JavaScript object , that looks like so:

var apps = {
    app1:
    [
        "ci-extension",
        "Unnamed",
        "<h1>Hello world!</h1>"
    ],
    app2:
    [
        "ci-extension",
        "Another one!",
        "Cool!"
    ]
}

The goal is to add a third key " demo " to the object and then push another three lines to it. So after all the pushing, the object should look like this:

var apps = {
    app1:
    [
        "ci-extension",
        "Unnamed",
        "<h1>Hello world!</h1>"
    ],
    app2:
    [
        "ci-extension",
        "Another one!",
        "Cool!"
    ],
    demo:
    [
        "ci-google",
        "My demo app!",
        "Some content"
    ]
}

What I tried?

I tried the following piece of code Object.keys(apps).push("demo"); (if this makes any sense). As an output, I just got 3 and the key "demo" was not added to the object.
And then to add items into demo I tried using this tiny piece of code Object.keys(apps)["demo"].push("blah blah blah..."); , but it totally did not work.

---

My brain and thoughts got obfuscated. Any help would be highly appreciated and very welcome. Thanks in advance!

Answer 1

You don't need to push() here, that's for adding to an exising array. You just want to add a key. The easiest way is like this:

apps.demo = [ "ci-google", "My demo app!", "Some content" ];

Or, equivalently

apps["demo"] = [ "ci-google", "My demo app!", "Some content" ];

The reason your code doesn't work is because Object.keys( apps ) creates you a new array containing all the keys in the apps object, but doing stuff to that array doesn't do anything to the actual apps object - you're just editing your new array. What you need to do is change the apps object directly (as I've shown above).

Answer 2

Note: Duncan's answer has the lowest learning curve.

With that said - especially since you are already using the .keys() method on the built-in Object type - two options you can look into are:

1. Object.assign()
2. Object.create()

Both methods will return new objects with properties included that you pass as the second argument to the function.

Object.assign(demo, {new_property}) will return an object with demo's own properties - thereby, neglecting the prototype chain.

Object.create(demo, {new_property}) will return an object that is prototype linked to demo.