Uncle Tom JavaScript

The problem with global variables is that both your JavaScript application and all the code on the Web page share these global variables, and they live in the same global namespace, so naming conflicts are unavoidable when two different parts of the program define global variables with the same name but with different effects.
The two features of JavaScript, unconsciously creating global variables are surprisingly easy. First, you can use variables without even needing to declare them; second, JavaScript has an implicit global concept, meaning that any variable you don't declare will become a global object property

function sum (x, y) {
   
   result = x + y;
   return result;
}

function foo () {
   var a = b = 0;
   // ...
}

Uncle Tom JavaScript