The following code produces a syntax error in Chrome and Firefox, but not Node.js:
{"hello": 1} However, the following code works everywhere:
var x = {"hello": 1} Also, the following works everywhere:
{hello: 1} What is the explanation for this strange behavior?
The NodeJS REPL evaluates code as an expression, by wrapping the code in parentheses, causing {"hello":1} to be ({"hello":1}) which is parsed successfully as an object literal.
Usually and elsewhere (in Chrome/Firefox's console), the curly braces are parsed as the delimiters of a block, like:
/*imagine if (true) */ { "hello": 1 // <-- What's this syntax? It's meaningless. } {hello:1} parses successfully, because hello in this context has the meaning of a label:
/*imagine if (true) */ { hello: 1; } // ^-- Automatic Semicolon Insertion The first example is not an object literal, it is a block. Blocks contain statements. The squence String literal, colon, Number literal is not a valid statement.
The second example is an object literal.
The third example is also a block, but you have replaced the string literal and colon with a label (which is allowed, but is pointless as there is no loop).
Context is important in JavaScript.
