Home
JS
JS
Tryit: JAVASCRIPT
运行 ❯
×
Change Orientation
Change Theme, Dark/Light
<!DOCTYPE html> <html> <body> <h2>JavaScript</h2> <p>要测试对象是否不存在，请测试类型是否未定义：</p> <p id="demo"></p> <script> document.getElementById("demo").innerHTML = typeof myObj === "undefined"; </script> </body> </html>