avoid memory leaks with closures. google javascript style guide.

memory leaks .js

// from google javascript style guide:
//   One thing to keep in mind, however, is that a closure keeps a pointer to its enclosing scope. As a 
//   result, attaching a closure to a DOM element can create a circular reference and thus, a memory leak. 
//   For example, in the following code: 

// Leaky example
function foo (element, a, b) {
  element.onclick = function() {
    // uses a and b
    // this func keeps a pointer to foo, its enclosing scope
    // this func is attached to element, which thus keeps a pointer to foo and its variables - a, b, element
  };
}

// the function closure keeps a reference to element, a, and b even if it never uses element. Since element 
// also keeps a reference to the closure, we have a cycle that won't be cleaned up by garbage collection. 
// In these situations, the code can be structured as follows:

// Solution example
function foo (element, a, b) {
  element.onclick = bar(a, b);
}

function bar (a, b) {
  return function() {
    //uses a and b
  }
}