<!DOCTYPE HTML><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>計時器</title><script type="text/javascript">? var num=0;? function startCount() {? ? document.getElementById('count').value=num;? ? num=num+1;? ? setTimeout("startCount()", 1000);? }? /*? ?*startCount();? ?*為什么不可以直接寫startCount()這個function,而是要寫setTimeout("startCount()",1000)?? ?*chrome的控制臺下報錯：? ?*Uncaught TypeError: Cannot set property 'value' of null? ?*at startCount (new_file.html?__hbt=1521883370139:9)? ?*at new_file.html?__hbt=1521883370139:15? ?*/? setTimeout("startCount", 1000);</script></head><body><form><input type="text" id="count" /></form></body></html>
直接使用startCount();
K8sCat
2018-03-24 17:32:21
