<html><body><h1>JavaScript 闭包</h1><p>使用局部变量计数。</p><button type="button" onclick="myFunction()">计数！</button><p id="demo">0</p><script>var add = (function () { var counter = 0; return function () {counter += 1; return counter;}})();function myFunction(){ document.getElementById("demo").innerHTML = add();}</script></body></html>