eval is evil, but is it flawed? [duplicate]

Question

If I run this:

eval('{ear: {"<=": 6}}'); 

I get an error:

Uncaught SyntaxError: Unexpected token :

Let's create the object manually:

var foo = {}; foo.ear = {}; foo.ear["<="] = 6; 

Now, the following code:

JSON.stringify(foo) 

Returns the following string:

'{"ear":{"<=":6}}'

The same string as the one I started with (except the white characters, but those are irrelevant), so eval(JSON.stringify(foo)) returns the same syntax error error message. However:

$.parseJSON(JSON.stringify(foo)) 

is executed correctly. What is the reason of that?

EDIT:

As nnnnnn and Ron Dadon pointed out, the initial string and the result of stringify are different. However, as I pointed out in the question, even the result of stringify used as input for eval will result in the syntax error message.

EDIT2:

Based on the answers and experiments conducted, this function is interesting:

function evalJSON(text) {     return eval("(" + text + ")"); } 

Answer 1

Main {} are parsed as block statement.

try to wrap in parenthesis:

eval('({ear: {"<=": 6}})'); 

In javascript {} can be parsed as a block or an object

examples:

//object var user = {   name: "John",   age: "32" };  //block {    let a = 5;    console.log(a);    }  //object: var a = {}; console.log({}); return {}; ({});  //block: function(){} for(k in o){} {} 

Answer 2

Object literal notations need to be evaluated. This happens when you assign a variable:

var a = {ear: {"<=": 6}}; 

or when you put parentheses around it, a anonymous object:

({ear: {"<=": 6}}); 

Otherwise curly brackets are parsed as block markers. In your case this means {ear:...} is a label definition, the label is named ear. The next block {"<=": 6} gives you a syntax error because "<=": 6 is invalid syntax.

The same applies if you put this into an eval statement.