js form verification method (practical)

//The following verifies the length
function checkTextLen(textId){
var len = 0;
var checkField=(textId);
var inputstring = ;
var string_length = ;
if (string_length == 0)
{
return 0;
}
for (var i=0;i<string_length;i++)
{
if ((i).charCodeAt()>255) len+=2;
else len+=1;
}
return len;
}
function checkTextLength(textId,length,msg){
var textObj =(textId);
if(checkTextLen(textId)>length/1){
alert("["+msg+"]"+"The maximum length is "+length+" bits, "+" please re-enter! Note: a Chinese character occupies 2 digits");
();
return false;
}else {
return true;
}
}
//The following verification does not contain illegal characters, Chinese, English, and numbers are all legal.
function isValidString(textId,errMsg){
szStr = (textId).value;
voidChar = "'\"><`~!@#$%^&\(\)（）！￥……？?“”‘'*";
for(i = 0 ; i < ; i ++){
aChar = (i, i + 1);
if((aChar) > -1){
alert(errMsg);
return false;
}
}
return true;
}
//The following verification can only enter letters, numbers, and underscores
function isEnglish(textId,errMsg)
{
s = (textId).value;
//The length of the following regular expression is between 6 and 20
//var patrn=/^(\w){6,20}$/;
var patrn =/^(\w)*$/;
if (!(s)){
alert(errMsg);
return false
}
return true
}
//The following verification is only allowed in Chinese
function isChinese(textId,errMsg)
{
s = (textId).value;
var patrn =/[^\u4E00-\u9FA5]/g;
if ((s)){
alert(errMsg);
return false
}
return true
}
//The following verification only allows numbers
function isNumber(textId,errMsg)
{
s = (textId).value;
//The length of the following regular expression is between 6 and 20
//var patrn=/^(\d){6,20}$/;
var patrn =/^(\d)*$/;
if (!(s)){
alert(errMsg);
return false
}
return true
}
Regular expressions using js are used to control that non-numbers are not allowed to be entered in text boxes, that is, only numbers are allowed to be entered. Call method: onkeyup="onlyNum(this);"
function onlyNum(obj)
{
temp = ;
//Note the following regular expressions, not enclosed in quotes. .
= (/\D/g,'');
}