代码示例:(标识:eg_js_mistakes_scope)
<!DOCTYPE html>
<html>
<body>

<h2>JavaScript</h2>

<p>JavaScript不会为每个代码块创建新的作用域。</p>

<p>此代码将显示 i(10)的值,即使在 for 循环块之外:</p>

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

<script>
for (var i = 0; i < 10; i++) {
  // some code
}
document.getElementById("demo").innerHTML = i;
</script>

</body>
</html>
运行结果: