Limit the number of text bytes in form JS Code _ form Effects

/*
Value: Values;
ByteLength: Database byte length
Title: Field Chinese name
Attribute: Property Name
Instructions for using:

Add (1) onkeyup= "Limitlength (this.value,100, ' name ', ' names ')"
(2) id= "name" or "Struts label" styleid= "name"
Note: The ID name and attribute property name are the same

Example: <textarea name= "Explain" id= "explain" onkeyup= "Limitlength" (value,5, ' semantic description ', ' explain ') ">

Or

<input type= "text" name= "explain" id= "explain" onkeyup= "Limitlength (value,5, ' semantic description ', ' explain ')" >

*/



function Limitlength (value, ByteLength, title, attribute) {
var newvalue = Value.replace (/[^\x00-\xff]/g, "* *");
var length = Newvalue.length;

When the number of bytes filled out is less than the number of bytes set
if (length * 1 <=bytelength * 1) {
Return
}
var limitdate = newvalue.substr (0, ByteLength);
var count = 0;
var limitvalue = "";
for (var i = 0; i < limitdate.length; i++) {
var flat = Limitdate.substr (i, 1);
if (flat = = "*") {
count++;
}
}
var size = 0;
var istar = newvalue.substr (ByteLength * 1-1, 1);//Check point is "x"

If base point is x; To determine if x is even or odd at the base point.
if (count% 2 = 0) {
When an even number is
Size = COUNT/2 + (bytelength * 1-count);
Limitvalue = value.substr (0, size);
} else {
When the number is odd
Size = (count-1)/2 + (ByteLength * 1-count);
Limitvalue = value.substr (0, size);
}
Alert (title + "Maximum Input" + ByteLength + "byte" (equivalent to "+bytelength/2+" characters)! ");
document.getElementById (attribute). value = Limitvalue;
Return
}