如何将变量用作对象中的键？

Question

Is this possible? The real world example is here:

var userKey = "userIdKey";

chrome.storage.sync.set({ userKey: "Hello World" }, function () {
    chrome.storage.sync.get(userKey, function (data) {
        console.log("In sync:", data);
    });

    console.log("Success");
});

This example currently fails because the getter looks for "userIdKey" where as the setter interprets the variable literally as "userKey"

UPDATE: I am fully aware of accessing a variable via array notation. The realworld example I have provided is for the creation of the object. I am hoping to ensure that the same key is always used for getting and setting -- rather than relying on two string constants being kept in sync.

Answer 1

var myObject = {},
    objectKey = 'Foo',
    myObject[objectKey] = 'Baz';

console.log(myObject[objectKey]);

Answer 2

The proper way is :

    var key = "something";
    Object.defineProperty(d, key, {
        get: function() {return this.getFullYear() },
        set: function(y) { this.setFullYear(y) }
    });

Or in your case:

chrome.storage.sync.defineProperty(this, userKey, {
    get: function() {return this[userKey];},
    set: function(value) {this[userKey] = value};
});

Read HERE for more on this. Object.prototype.defineProperty is new and not available in legacy mode, but the polyfill is available as Object.prototype.__defineGetter__ and Object.prototype.__defineSetter__ .

Answer 3

Access it like an array:

myObject['Foo']

To set:

myObject['Foo'] = "Bar"

Or as a variable:

var key = "Foo";
myObject[key] = "Bar"