Eval() = Unexpected token : error

You have to write like this

eval('('+stringJson+')' );

to convert an string to Object

Hope I help!

FWIW, use JSON.parse instead. Safer than eval.

Because eval does not force an expression context and the string provided is an invalid JavaScript program, thus the first three tokens (and how they are looked at) are:

{            // <-- beginning of a block, and NOT an Object literal
"Topics"     // <-- string value, okay (note this is NOT a label)
:            // <-- huh? expecting ";" or "}" or an operator, etc.

Happy coding.