js随笔

javascript(js)的trim()函数的两种定义及用法
方法一：
<script language="javascript">
String.prototype.trim = function(){      //定义trim()函数
    var reExtraSpace = /^\s*(.*?)\s+$/;
     return this.replace(reExtraSpace,"$1");
}
function check(ok){       //表单验证函数
     if(ok.username.value.trim() == ""){
        alert("请输入用户名！");
       ok.username.focus();
       return false;
    }
}
</script>

方法二：
<script language="javascript">
function trim(str)        //定义trim()函数
{
          return str.replace(/^\s*(.*?)[\s\n]*$/g, '$1');
}
function check()      //表单验证函数
{
      if(trim(document.login.username.value) == "")
      {
          alert("请输入用户名！");
          document.login.username.focus();
          return false;
      }
}

</script>
 

判断日期正则表达式
<script language=javascript>
 function isValidDate(dateStr) {
        var matchArray = dateStr.match(/^[0-9]+-[0-1][0-9]-[0-3][0-9]$/)
        if (matchArray == null) {
          alert("Invalid date: " + dateStr);
          return false;
        }
        return true;
      }

String.prototype.isDate = function()
{
   var r = this.match(/^(\d{1,4})(-|\/)(\d{1,2})\2(\d{1,2})$/);
   //var r = this.match(/^d{4}-(0?[1-9]|[1][012])-(0?[1-9]|[12][0-9]|[3][01])[s]+d([0-1][0-9]|2?[0-3]):([0-5][0-9]):([0-5][0-9])$/);
   //var r = this.match(/^((((1[6-9]|[2-9]\d)\d{2})-(0?[13578]|1[02])-(0?[1-9]|[12]\d|3[01]))|(((1[6-9]|[2-9]\d)\d{2})-(0?[13456789]|1[012])-(0?[1-9]|[12]\d|30))|(((1[6-9]|[2-9]\d)\d{2})-0?2-(0?[1-9]|1\d|2[0-8]))|(((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))-0?2-29-))$/);
   if(r==null)return false; var d = new Date(r[1], r[3]-1, r[4]);
   return (d.getFullYear()==r[1]&&(d.getMonth()+1)==r[3]&&d.getDate()==r[4]);
}
//alert("20020131\n" + "20020131".isDate());
//alert("2002-01-31".isDate());

String.prototype.isTime = function()
{
  var r = this.match(/^(\d{1,4})(-|\/)(\d{1,2})\2(\d{1,2}) (\d{1,2}):(\d{1,2}):(\d{1,2})$/);
  if(r==null)return false; var d = new Date(r[1], r[3]-1,r[4],r[5],r[6],r[7]);
  return (d.getFullYear()==r[1]&&(d.getMonth()+1)==r[3]&&d.getDate()==r[4]&&d.getHours()==r[5]&&d.getMinutes()==r[6]&&d.getSeconds()==r[7]);
}
//alert("2002-1-31 12:34:56".isTime());
//alert("2001-2-29 12:54:56".isTime());
//alert("2002-1-41 12:00:00".isTime());

function isDate(str){
 if(8 == str.length){
  str = str.substring(0,4) + "-" + str.substring(4,6) + "-" + str.substring(6,8);
 }
var reg = /^((((1[6-9]|[2-9]\d)\d{2})-(0?[13578]|1[02])-(0?[1-9]|[12]\d|3[01]))|(((1[6-9]|[2-9]\d)\d{2})-(0?[13456789]|1[012])-(0?[1-9]|[12]\d|30))|(((1[6-9]|[2-9]\d)\d{2})-0?2-(0?[1-9]|1\d|2[0-8]))|(((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))-0?2-29-))$/
if (reg.test(str)) return true;
return false;
}
var str = "12345678";
str = str.substring(0,4) + "-" + str.substring(4,6) + "-" + str.substring(6,8);
//alert(str);
//alert("20000131"+isDate("20000131"));
//alert("2000-01-31"+isDate("2000-01-31"));
</script>

<script type="text/javascript">
<!--
function isDate(me){
var str = me.value;
 if(8 == str.length){
  str = str.substring(0,4) + "-" + str.substring(4,6) + "-" + str.substring(6,8);
 }
var reg = /^((((1[6-9]|[2-9]\d)\d{2})-(0?[13578]|1[02])-(0?[1-9]|[12]\d|3[01]))|(((1[6-9]|[2-9]\d)\d{2})-(0?[13456789]|1[012])-(0?[1-9]|[12]\d|30))|(((1[6-9]|[2-9]\d)\d{2})-0?2-(0?[1-9]|1\d|2[0-8]))|(((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))-0?2-29-))$/
if (reg.test(str)) {
 me.value = str;
}
}
//-->
</script>

 多个共存,字符串长度控制

<script type="text/javascript">
function strlen(me,len){
 var i = me.value.replace(/[^\x00-\xff]/g,"**").length;
 var d = ""!=me.id?me.id:me.name;
 var hiddenid = "CLF"+d;
 var o = document.getElementById(hiddenid);
 if(null != o){
  if(i > len){
   me.value = o.value;
  }else{
   o.value = me.value;
  }
 }
}
 </script>
 
 <input name="sss" onkeyup="strlen(this,20)" >
 <input id="CLFsss" type="hidden"  >