I've Heard Global Variables Are Bad, What Alternative Solution Should I Use?

Question

I\'ve read all over the place that global variables are bad and alternatives should be used. In Javascript specifically, what solution should I choose.

I\'m thinking

Answer 1

Global state causes problems in several areas. One is code reuse. When you access some global state that means the component must be aware of it's environment(something outside of itself). You should avoid this as much as possible, because it makes the component unpredictable.

Say I have an object that accesses your globalVariables function and I want to use it in another page. How do I know to define the globalVariables object or even how to define it? However if you can pass the information into a constructor or as an argument to a function then I can easily determine what is required by the object.

Also when you access or modify the global scope then you risk affecting other objects. This is why libraries like jquery use only a single name on the global scope(the least possible). It lessens the possibility of conflict with other libraries. In other words the global scope is out of your control, so it is dangerous.