Question

I’d like to do something like the following w/o using eval(). What’s the best way to do that?

config: function(config) {
  for (var key in config) {
    if (config.hasOwnProperty(key)) {
      console.log('setting: ' + key + ' = ' + config[key]);
      eval(key + ' = "' + config[key] + '"');
    }
  }
}

Answer 1

You don’t have JSON. You have a normal JavaScript object. You can make the keys to global variables by setting them as properties of the window object (all global variables are properties of the window object and using eval makes them global):

window[key] = config[key];

But note that this might overwrite already set values or even nativ window properties. To avoid this, you might want to test whether the property already exists first:

if(!(key in window)) {
    window[key] = config[key];
}

As global variables are bad, it might be better to assign the properties only to the object where the config function is defined on. This would be this[key] = config[key] if you call the function with obj.config(someConfiguration).

In any way you have to assign them to some object. You cannot make them local to a function otherwise. In the end it depends on where you want to have access to the configuration values.