eval.js

function eval(str, context, expose) {
    var exposeKeys = [];
    var exposeValues = [];
    var i;
    for (i in expose) {
        if (Object.hasOwnProperty.call(expose, i)) {
            exposeKeys.push(i);
            exposeValues.push(expose[i]);
        }
    }
    return (new Function(
        'return function(' + exposeKeys + ') { return function() { ' + str + ' }.bind(this) }'
    ))().apply(context, exposeValues);
}

var ctx = {};
var expose = {
    up: function(str) {
            return str.toUpperCase();
        }
};

var f = eval('console.log(this, arguments); return up("aaa")', ctx, expose);
console.log(f.toString());
var t = f('Look! Even has args!');
console.log(t);