Question

Possible Duplicate:
What is the difference between object keys with quotes and without quotes?

I mostly know JavaScript from using it, but there’s something I don’t understand yet.

What’s the difference between these two object literals:

var obj1 = {
   myProp: '123'
};

var obj2 = {
   'myProp': '123'
};

Are they just ‘synonyms’, or is there a subtle difference?

Thanks!

Answer 1

In the object initializer syntax, keys can be numeric literals, identifiers, or strings.

var obj1 = {
    1e9: "123" //valid because it's a numeric literal
}

var obj2 = {
    $_ASd: "123" //Valid because it's a valid identifier I.E. you could make a variable called $_Asd
}

var obj3 = {
    $ hello world: "123" //invalid because it's not an identifier, I.E. you could not make a variable called $ hello world
}

var obj4 = {
    '$ hello world': "123" //valid because it's a valid string
}

After that the key is turned into a string regardless of what it was in the syntax, so in the case of 1e9 the key will be a string "1000000000".