<!DOCTYPE html> <html> <head> <title>js</title> <meta charset="utf-8"> <style> #box { width: 150px; height: 150px; background-color: red; } </style> </head> <body> <div id='box'></div> </body> <script> var box = document.getElementById('box'); alert(box) </script> </html><!DOCTYPE html> <html> <head> <title>js</title> <meta charset="utf-8"> <style> #box { width: 150px; height: 150px; background-color: red; } </style> </head> <body> <div id='box'></div> </body> <script> var box = document.getElementById('box'); document.write(box) </script> </html><!DOCTYPE html> <html> <head> <title>js</title> <meta charset="utf-8"> <style> #box { width: 150px; height: 150px; background-color: red; } </style> </head> <body> <div id='box'></div> </body> <script> var box = document.getElementById('box'); console.log(box) </script> </html><!DOCTYPE html> <html> <head> <title>js</title> <meta charset="utf-8"> <style> #box { width: 150px; height: 150px; background-color: red; } </style> </head> <body> <div id='box'></div> </body> <script> var box = document.getElementById('box'); console.dir(box) </script> </html>文章来源: 03-调试方法