JSON.parse unexpected token s

Question

Why is it that whenever I do :-

JSON.parse('"something"') 

it just parses fine but when I do:-

var m = "something"; JSON.parse(m); 

it gives me an error saying:-

Unexpected token s 

Answer 1

You're asking it to parse the JSON text something (not "something"). That's invalid JSON, strings must be in double quotes.

If you want an equivalent to your first example:

var s = '"something"'; var result = JSON.parse(s); 

Answer 2

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.