Google JavaScript Style Guide上看到一段关于闭包的写法，先贴内容：
 
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:
 


function foo(element, a, b) {
 element.onclick = function() { /* uses a and b */ };
}

 
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:
 

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

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