Javascript create function from string

Question

I need to "parse"/create JS function from string. Lets say:

var str = "function(data,type,full,meta){ return'works';}";

I tried to use javascript eval(str) function but I always get this error from console when trying this

eval(str)

Uncaught SyntaxError: Unexpected token (

VM:2323:1

I don't see anyting wrong with the syntax.

Answer 1

That's because there is nothing which forces it to be parsed as a function expression, so it's parsed as a function declaration.

And function declarations require a name. From Function Definition ,

 FunctionDeclaration : function Identifier ( FormalParameterList opt ) { FunctionBody } FunctionExpression : function Identifier opt ( FormalParameterList opt ) { FunctionBody } 

An easy fix (if you are sure the string has a proper syntax) would be wrapping it in parentheses. Then it will be parsed as a function expression.

eval('(' + str + ')')