Pure JavaScript functions for form validation, character counter, int validation, float validation, email validation, multiple SelectBox validation-
Here are few functions which can be used in any application for javascript validation. Since they don't require any library like jQuery to function they are very lightweight.
<script type="text/javascript">
//remove white spaces
function trim(s){
var l=0;
var r=s.length-1;
while(l<s.length && s[l]==' '){
l++;
}
l++;
}
while(r>l && s[r]==' '){
r-=1;
}
r-=1;
}
return s.substring(l,r+1);
}
//email validation with regular expression
//email validation with regular expression
function checkEmail(email2) {
var regMail = /^([_a-zA-Z0-9-]+)(\.[_a-zA-
if(regMail.test(email2)==
return false;
} else {
return true;
}
return false;
} else {
return true;
}
}
// example of form validation. call in <form onsubmit="return validate(this)">
function validate(obj){
if(trim(obj.name.value)==''){
alert("Please Enter Name");
obj.name.focus();
return false;
} else if(trim(obj.email.value)==''){
alert("Please Enter Email");
obj.email.focus();
return false;
} else if(!checkEmail(obj.email.
alert("Please provide valid Email");
obj.email.focus();
return false;
} else {
return true;
}
return true;
}
}
//string length counter in textbox or textarea
//string length counter in textbox or textarea
function textCounter(fieldid, countfield){
field=document.getElementById(
var maxlimit=500;
if (field.value.length > maxlimit)
field.value = field.value.substring(0, maxlimit);
else document.getElementById(
}
//Regular exepression validation for int validation
function test1(str){
return /^ *[0-9]+ *$/.test(str);
}
//Regular exepression validation for floatvalidation
function validateDecimal(value){
return /^\d*\.?\d*$/.test(value);
}
/// keyCode validation for float values
function check_float(e,field){
if (!(((e.keyCode>=48)&&(e.
e.keyCode=0;
return false;
}
if (e.keyCode==46){
var patt1=new RegExp("\\.");
var ch =patt1.exec(field);
if(ch=="."){
e.keyCode=0;return false;
}
}
return true;
}
//keyCode validation for numeric values can be enter in text box
function isNumberKey(evt) {
var charCode = (evt.which) ? evt.which : event.keyCode
if (charCode > 31 && (charCode < 48 || charCode > 57))
return false;
return true;
}
//multiple select box validation
function validate(obj){
if(document.frm["state[]"].
alert('Please choose State');
return false;
}
return true;
}
// or multiple select box validation
function validate(obj){
var expr=0;
for(ex=0;ex<obj.elements['ex_
if(obj.elements['ex_name[]'][
expr=1;
}
}
if(expr==0){
alert("Please Select Name of Consignor / Exporter!");
return false;
}
}
</script>
</script>
