What is the purpose of wrapping whole JavaScript files in anonymous functions?

The purpose of wrapping is to a namespace and control the visibility of member functions. It wraps the code inside a function scope and decreases clashing with other libraries. This is what we call Immediately Invoked Function Expression (IIFE) or Self Executing Anonymous Function.

Syntax

Here’s the syntax −

(function() {
   // code
})();

As you can see above, the following pair of parentheses converts the code inside the parentheses into an expression −

function(){...}

In addition, the next pair, i.e. the second pair of parentheses continues the operation. It calls the function, which resulted from the expression above.