[javascript] Which characters are valid/invalid in a JSON key name?

Are there any forbidden characters in key names, for JavaScript objects or JSON strings? Or characters that need to be escaped?

To be more specific, I'd like to use "$", "-" and space in key names.

Unicode codepoints U+D800 to U+DFFF must be avoided: they are invalid in Unicode because they are reserved for UTF-16 surrogate pairs. Some JSON encoders/decoders will replace them with U+FFFD. See for example how the Go language and its JSON library deals with them.

So avoid "\uD800" to "\uDFFF" alone (not in surrogate pairs).

It is worth mentioning that while starting the keys with numbers is valid, it could cause some unintended issues.

Example:

var testObject = {
    "1tile": "test value"
};
console.log(testObject.1tile); // fails, invalid syntax
console.log(testObject["1tile"]; // workaround

The following characters must be escaped in JSON data to avoid any problems:

• " (double quote)
• \ (backslash)
• all control characters like \n, \t

JSON Parser can help you to deal with JSON.