demo page can't handle {a:"b"}

[jshint]

demo page can't handle {a:"b"}

[GarrettS]

This bug is invalid.

An ExpressionStatement must not begin with either '{' or 'function ' because that would make it ambiguous with a Block or a FunctionDeclaration, respectively. Thus, {a : "b" } is not a valid Program.

[valueof]

To clarify further, expression in JavaScript can't start with { so whenever JSHint sees that it switches to JSON mode. And in JSON, all keys must be strings. So, if you'll try: { "a": "b" } the check will pass.

[makc]

expression in JavaScript can't start with {

why does javascript:{a:"b"}; not present me same error message?

[makc]

you can also try this html in your browser of choise:

<script>{a:alert("orly");}</script>

[makc]

(github ate my script tags)

[valueof]

I'd assume they either eval it or run it in a closure with assumed return? I am not sure though. Does anybody actually use this in real-world projects? Does it work in all browsers?

[makc]

I assume lots of people use it in var foo = { ... } kind of statements, but there's nothing to prevent you from using it without "var foo = " part; just like you could write 2 + 3; and it'd still be valid script.

[GarrettS]

The switching between JSON and ECMAScript happens automatically, I see.

Have you considered having this be explicit choice? The potential problem is when the user enters what he believes is JSON but in actuality it is not, but it is valid Ecmascript. For example:

[
  { a : "b" }
]

Not valid JSON but valid Ecmascript.

[valueof]

GarrettS, I agree. This switching was a part of JSLint, I am looking into making it explicit.