var end = start +...

var end = start + document.cookie.indexOf(";",start); 这一行代码为什找不到返回-1

<!DOCTYPE html><html> <head> <meta charset="utf-8" /> </head> <script type="text/javascript"> //检测cookie function getcookie(myname) { if (document.cookie.length > 0) { var start = document.cookie.indexOf(myname + "="); if (start != -1) { start = start + myname.length + 1; var end =document.cookie.indexOf(";", start); if (end == -1) { end = document.cookie.length; } return unescape(document.cookie.substring(start, end)); } } return "" } //创建cookie function setcookie(myname, value, expireday) { var exdate = new Date(); exdate.setDate(exdate.getDate() + expireday); document.cookie = myname + "=" + escape(value) + ((expireday == null) ? "" : ";expires=" + exdate.toGMTString()) } function checkcookie() { username = getcookie('username') if (username != null && username != "") { alert('Welcome again ' + username + '!') } else { username = prompt('Please enter your name:', "") if (username != null && username != "") { setcookie('username', username, 365) } } } </script> <body onload="checkcookie()"></body></html>

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柠檬酸钠

TA贡献331条经验获得超534个赞

也就是说从start开始只剩下一个或者没有cookie了，所以找不到分号，返回-1了

1 反对回复 2016-06-28

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var end = start + document.cookie.indexOf(";",start); 这一行代码 为什找不到 返回-1

var end = start + document.cookie.indexOf(";",start); 这一行代码 为什找不到 返回-1

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var end = start + document.cookie.indexOf(";",start); 这一行代码为什找不到返回-1

var end = start + document.cookie.indexOf(";",start); 这一行代码为什找不到返回-1