请大家帮忙看一下这一段代码中的问号用在这里是什么意思呀,我是从教材上看到的,谢谢了。function SetCookie (name, value, expires, path, domain, secure)
{
var expString = ((expires == null) ? "" : ("; expires=" + expires.toGMTString()));
var pathString = ((path == null) ? "" : ("; path=" + path));
var domainString = ((domain == null) ? "" : ("; domain=" + domain));
var secureString = ((secure == true) ? "; secure" : "");
document.cookie = name + "=" + escape (value) +expString + pathString + domainString +secureString;
}
{
var expString = ((expires == null) ? "" : ("; expires=" + expires.toGMTString()));
var pathString = ((path == null) ? "" : ("; path=" + path));
var domainString = ((domain == null) ? "" : ("; domain=" + domain));
var secureString = ((secure == true) ? "; secure" : "");
document.cookie = name + "=" + escape (value) +expString + pathString + domainString +secureString;
}
得到的s=5;
var pathString = ((path == null) ? "" : ("; path=" + path));
假设path == null条件为真,那么pathString就为"",否则pathString =("; path=" + path)
var expString = ((expires == null) ? "" : ("; expires=" + expires.toGMTString()));
就比如这个,如果expires == null成立,expString值为空,反之就为(; expires=" + expires.toGMTString()));
var pathString = ((path == null) ? "" : ("; path=" + path));
如果path为null就返回"",否则就返回:后面的值。
var a =1;
var b=0;
if(a>b)?true:false;
即if(a>b){
return true;
}else{
return false;
}