javascript中各种格式的正则表达式验证函数实现

/验证email/
var str=email;
var expression = /\w+([-+.']\w+)@\w+([-.]\w+)\.\w+([-.]\w+)*/;
var objExp = new RegExp(expression);
if(objExp.test(str) == true){
return true ;
}else
return false;

/验证电话号码/
var str=tel;
var expression=/(\d{3}-?\d{8}|(\d{4}-)(\d{7})/;
var objExp = new RegExp(expression);
if(objExp.test(str) == true){
return true ;
}else
return false;

/验证是否是汉字/
var str=name;
var expression = /[\u4E00-\u9FA5/;
var objExp = new RegExp(expression);
if(objExp.test(str) == true){
return true ;
}else
return false;

/验证身份证号码/
var str=NO;
var expression = /\d{17}[\d|X]|\d{15}/;
var objExp = new RegExp(expression);
if(objExp.test(str) == true){
return true ;
}else
return false;

/验证网址是否合法/
var str=url;
var expression = /http(s)?:\/\/([\w-]+\.)+[\w-]+(/[\w- ./?%&=]*)?/;
var objExp = new RegExp(expression);
if(objExp.test(str) == true){
return true ;
}else
return false;

/限制字符串长度str为指定字符串，digit为指定最大长度/
function checkstr(str,digit)
{
var n=0;
for(int i=0;i<str.length;i++)
{
var leg=str.charCodeAt(i);
if(leg>255)
{
n+=2;
}else
n+=1;
}
if(n>digit)
{
return true;
}else
return false;
}