What is the difference between this
var person = {
name: "Bob",
age: "99"
};
and this?
var person = {
"name": "Bob",
"age": "99"
};
Or do they mean the same thing? If they do, what if I want the key to be an object? How would I specify the object as the key if name means "name"?
There is no difference. Quotes are only necessary if you want to use a string as a property name, but that string is not a valid identifier. Further,
An object property name can be any valid JavaScript string, or anything that can be converted to a string, including the empty string. However, any property name that is not a valid JavaScript identifier (for example, a property name that has space or dash, or starts with a number) can only be accessed using the square bracket notation.
foo bar is a string and is not a valid identifier and is not a keyword in any programming language I know. Furthermore, term string in programming is a data type or/and class, in some languages equivalent of array of chars. Keywords are a subset of words or tokens - they are called reserved words too as they have special meaning in language grammar. But you can't even say that keyword can't be identifier - this is a keyword and an identifier as well in javascript.They are equivalent in this case, but the quoted version allows you to use keys that are not valid JS identifiers. For example, this does not work:
{ -test: 42 }
while this does:
{ "-test": 42 }
You cannot specify an object as the key no matter what.
console.log(h) to see what happened. Not what you thought.
Object {[object Object]: 1}console.log("[object Object]") will print 1. As you see, the key is not really an object.They mean the same thing. Valid keys are identifiers, string literals, or numeric literals. See http://ecma-international.org/ecma-262/5.1/#sec-11.1.5
You can't yet use objects themselves as keys, but WeakMap objects as proposed for EcmaScript 6 will solve this. See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap
"object"is a perfectly valid property name."object"is not a valid property name? I don't even sayx = {object: "foo"};is invalid! It is valid but the keyobjectofxis converted implicitly to string"object"and has nothing to do withobjectfrom global namespace. Misleading? Yes, using keys likeobjector"object"is misleading, confusing etc. And don't try to tell me that string is an object too. I know that. The main thing is that whatever the key is, it will be converted to string if it isn't string already. No way to have "object key" with custom methods and attrs.