Javascript: Validation

lib_validation.js

//if the ext is invalid, display an alert and return false.
//if is valid returns true.
function ValidateExtImg(inputObj) {
    var _validFileExtensions = [".jpg", ".jpeg", ".bmp", ".gif", ".png", ".pdf"];
    var oInput = inputObj;
    if (oInput.type == "file") {
        var sFileName = oInput.value;
        if (sFileName.length > 0) {
            var blnValid = false;
            for (var j = 0; j < _validFileExtensions.length; j++) {
                var sCurExtension = _validFileExtensions[j];
                if (sFileName.substr(sFileName.length - sCurExtension.length, sCurExtension.length).toLowerCase() == sCurExtension.toLowerCase()) {
                    blnValid = true;
                    break;
                    }
                }

                if (!blnValid) {
                    alert("Sorry, " + sFileName + " is invalid, allowed extensions are: " + _validFileExtensions.join(", "));
                    return false;
                }
            }
        }

    return true;
}


/**************************************
/*   size file upload
/**************************************/
//return file size in bytes
function getFileSize( inputFile ) {
    var files = inputFile.files;
 
    if( !files ) {
        //for IE
        try {
            var fs = new ActiveXObject( 'Scripting.FileSystemObject' );
            var file = fs.getFile( inputFile.value );
            return file.size;
        } catch( ex ) {
            return -1;
        }
 
    } else if( files.length > 0 ) {
        //for rest of the world
        return files[ 0 ].size;
    }
}


//**********************************************************DATE******************************************************
/* DHTML date validation script. Courtesy of SmartWebby.com (http://www.smartwebby.com/dhtml/datevalidation.asp)
// Declaring valid date character, minimum year and maximum year*/
// example: ValidateDate(inputField)
// returns true if is ok else display alerts depending failure and returns false.

var dtCh= "/";
var minYear=1900;
var maxYear=2100;

function isInteger(s){
    var i;
    for (i = 0; i < s.length; i++){   
        // Check that current character is number.
        var c = s.charAt(i);
        if (((c < "0") || (c > "9"))) return false;
    }
    // All characters are numbers.
    return true;
}

function stripCharsInBag(s, bag){
    var i;
    var returnString = "";
    // Search through string's characters one by one.
    // If character is not in bag, append to returnString.
    for (i = 0; i < s.length; i++){   
        var c = s.charAt(i);
        if (bag.indexOf(c) == -1) returnString += c;
    }
    return returnString;
}

function daysInFebruary (year){
    // February has 29 days in any year evenly divisible by four,
    // EXCEPT for centurial years which are not also divisible by 400.
    return (((year % 4 === 0) && ( (!(year % 100 === 0)) || (year % 400 === 0))) ? 29 : 28 );
}
function DaysArray(n) {
    for (var i = 1; i <= n; i++) {
        this[i] = 31;
        if (i==4 || i==6 || i==9 || i==11) {this[i] = 30;}
        if (i==2) {this[i] = 29;}
   } 
   return this;
}

function isDate(dtStr){
    var daysInMonth = DaysArray(12);
    var pos1=dtStr.indexOf(dtCh);
    var pos2=dtStr.indexOf(dtCh,pos1+1);
    var strDay=dtStr.substring(0,pos1);
    var strMonth=dtStr.substring(pos1+1,pos2);
    var strYear=dtStr.substring(pos2+1);
    strYr=strYear;
    if (strDay.charAt(0)=="0" && strDay.length>1) strDay=strDay.substring(1);
    if (strMonth.charAt(0)=="0" && strMonth.length>1) strMonth=strMonth.substring(1);
    for (var i = 1; i <= 3; i++) {
        if (strYr.charAt(0)=="0" && strYr.length>1) strYr=strYr.substring(1);
    }
    month=parseInt(strMonth,10);
    day=parseInt(strDay,10);
    year=parseInt(strYr,10);
    if (pos1==-1 || pos2==-1){
        alert("The date format should be : dd/mm/yyyy");
        return false;
    }
    if (strMonth.length<1 || month<1 || month>12){
        alert("Please enter a valid month");
        return false;
    }
    if (strDay.length<1 || day<1 || day>31 || (month==2 && day>daysInFebruary(year)) || day > daysInMonth[month]){
        alert("Please enter a valid day");
        return false;
    }
    if (strYear.length != 4 || year===0 || year<minYear || year>maxYear){
        alert("Please enter a valid 4 digit year between "+minYear+" and "+maxYear);
        return false;
    }
    if (dtStr.indexOf(dtCh,pos2+1)!=-1 || isInteger(stripCharsInBag(dtStr, dtCh))===false){
        alert("Please enter a valid date");
        return false;
    }
return true;
}

function ValidateDate(date_id){
    var dt=document.getElementById(date_id.id);
    if (isDate(dt.value)===false){
        dt.focus();
        return false;
    }
    return true;
 }
//**********************************************************DATE***********************************************************************



function echeck(str) { //Email check function

    var at="@";
    var dot=".";
    var lat=str.indexOf(at);
    var lstr=str.length;
    var ldot=str.indexOf(dot);
    if (str.indexOf(at)==-1){
       return false;
    }

    if (str.indexOf(at)==-1 || str.indexOf(at)===0 || str.indexOf(at)==lstr){
       return false;
    }

    if (str.indexOf(dot)==-1 || str.indexOf(dot)===0 || str.indexOf(dot)==lstr){
        return false;
    }

     if (str.indexOf(at,(lat+1))!=-1){
        return false;
     }

     if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot){
        return false;
     }

     if (str.indexOf(dot,(lat+2))==-1){
        return false;
     }

     if (str.indexOf(" ")!=-1){
        return false;
     }

}
function emailVal(emailId)
    {
    if ((emailId.value===null)||(emailId.value==="")){
        alert("You must enter your email.");
        email.focus();
        return false;
    }

    if (echeck(emailId.value)===false){
        alert("There seems to be a problem with the email entered.");
        emailId.focus();
        return false;
    }
   
    }