If all you want to do is pass arbitrary values into some evaluated code, Function() works for that, and it doesn't use the local scope:
var foo = (function () {
var n = {};
return function ( s ) {
return Function( "n",
"\"use strict\";\n" +
"return (\n" +
s + "\n" +
");\n" +
"//@ sourceURL=foo"
)( n );
};
})();
foo( "n.foo = 5" );
foo( "n.foo + 10" );
Technically this implementation accepts a different segment of JavaScript syntax than yours does, but I doubt you care about that in particular.
It's nice that JavaScript provides a way to evaluate code in a local scope, but so far I haven't had much excuse to do that. Occasionally, I do insert an eval( "" ) just to force a closure to capture every single variable in its surrounding lexical scope, since that makes it possible to interact with all those variables when paused there in the Chrome Debugger.
Yes, I tried that but I found it to be significantly slower than using eval. It also requires you to use "return" if you want to actually return the value, whereas eval returns it automatically.
