What you are passing to JSON.parse method must be a valid JSON after removing the wrapping quotes for string.
so something is not a valid JSON but "something" is.
A valid JSON is -
JSON = null
/* boolean literal */
or true or false
/* A JavaScript Number Leading zeroes are prohibited; a decimal point must be followed by at least one digit.*/
or JSONNumber
/* Only a limited sets of characters may be escaped; certain control characters are prohibited; the Unicode line separator (U+2028) and paragraph separator (U+2029) characters are permitted; strings must be double-quoted.*/
or JSONString
/* Property names must be double-quoted strings; trailing commas are forbidden. */
or JSONObject
or JSONArray
Examples -
JSON.parse('{}'); // {}
JSON.parse('true'); // true
JSON.parse('"foo"'); // "foo"
JSON.parse('[1, 5, "false"]'); // [1, 5, "false"]
JSON.parse('null'); // null
JSON.parse("'foo'"); // error since string should be wrapped by double quotes
You may want to look JSON.