html运行实例（eg_js_function_closures

代码示例：（标识：eg_js_function_closures_4）

<!DOCTYPE html>
<html>
<body>

<h1>JavaScript 函数闭包</h1>

<p>使用局部变量计数。</p>

<p id="demo">0</p>

<script>
document.getElementById("demo").innerHTML = add();
function add() {
  var counter = 0;
  function plus() {counter += 1;}
  plus();  
  return counter; 
}
</script>

</body>
</html>