Get object by name as string without eval

Question

The code below does what I want, but I would like to avoid eval. Is there a function in Javascript that looks up an object by its name as defined by in a string?

myobject = {"foo" : "bar"}
myname = "myobject";
eval(myname);

Some context: I am using this for an application in which a large number of nodes in the dom has a html5 data-object attribute, which is used in the handler function to connect back to the model.

Edit: myobject is neither global nor local, it is defined in one of the parent frames of the handler.

Solution 1

If variables are global then:

myobject = {"foo" : "bar"};
myname = "myobject";
window[myname].foo

DEMO

For local:

(function(){
    myobject = {"foo" : "bar"};
    myname = "myobject";
    alert( this[myname].foo );
})();

DEMO

Solution 2

Local Variable Solution:

You could make all objects that you want to access with a string properties of another object. For example:

var objectHolder = {
    myobject: {"foo" : "bar"},
    myobject2: {"foo" : "bar"},
    myobject3: {"foo" : "bar"}
};

And then access your desired object like this:

var desiredObject = objectHolder["myobject"];

---

Global Variable Solution:

You can access global variables using a string like this:

window["myobject"];

Solution 3

This question is pretty old, but since it's the top result on Google for the query "javascript get object from string", I thought I'd share a technique for longer object paths using dot notation.

Given the following:

var foo = { 'bar': { 'alpha': 'beta' } };

We can get the value of 'alpha' from a string like this:

var objPath = "bar.alpha";

var alphaVal = objPath.split('.')
  .reduce(function (object, property) {

    return object[property];
  }, foo);

// alphaVal === "beta"

If it's global:

window.foo = { 'bar': { 'alpha': 'beta' } };

Just pass window as the initialValue for reduce:

var objPath = "foo.bar.alpha";

var alphaVal = objPath.split('.')
  .reduce(function (object, property) {

    return object[property];
  }, window);

// alphaVal === "beta"

Basically we can use reduce to traverse object members by passing in the initial object as the initialValue.

MDN article for Array.prototype.reduce

Solution 4

since window is a global namespace, you could simply use

window[myname]

View more solutions

Comments

[thecodeparadox]

@ŠimeVidas I know Sir, just for OP's case. Thanks

[darksky]

You probably forgot to replace the equal signs with colons in the first part of your post.

[Loilo]

Your second example is a kind of misleading. It's basically the same as the first one - you define myobject without var (means: globally) and then access it by window[myname] (because this === window, in your case). As soon as your context (your this) changes, your example won't work anymore. Long story short: That's not a way to access local variables by name.