Equality of object property names depends on code units

Today I was writing a quick blog post on hidden characters in object property names, and while writing it I came across today's learning.

The ECMAScript spec describes equality for property names as follows:

An object can have two properties that look the same but consist of different code units. Let's look at an example.

const unicodeObject = {
    ü: 'foo',
    u\u0308: 'bar'
}

// evaluates to:
// {ü: "foo", ü: "bar"}

The properties look the same but are not because they consist of different code units. If you're interested in more details on property names, check out my blog post "Hidden messages in JavaScript property names", there is way more cool (and scary) stuff in it. ;)