<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<script>
var area = 'Beijing';
function getArea(){
return this.area;
}
console.log(area); // 访问变量，输出结果：Beijing
console.log(window.area); // 访问window对象的属性，输出结果：Beijing
console.log(getArea()); // 调用自定义函数，输出结果：Beijing
console.log(window.getArea()); // 调用window对象的方法，输出结果：Beijing
console.log(window.Number(area)); // 调用内置函数，将变量area转换为数值型，输出结果：NaN
</script>
</body>
</html>