i was checking a sample signup.php script from a book ...and i read about the use of javascript for form validation ... signup.php <html> <head> <script> types of form validation checkuser.php these were the parts of that signup.php page ... what are all the types of form validation out there ? types of form ... types of form validation ... types of input feild validations.. <script type='text/javascript'> function formValidator(){ // Make quick references to our fields var firstname = document.getElementById('firstname'); var addr = document.getElementById('addr'); var zip = document.getElementById('zip'); var state = document.getElementById('state'); var username = document.getElementById('username'); var email = document.getElementById('email'); // Check each input in the order that it appears in the form! if(isAlphabet(firstname, "Please enter only letters for your name")){ if(isAlphanumeric(addr, "Numbers and Letters Only for Address")){ if(isNumeric(zip, "Please enter a valid zip code")){ if(madeSelection(state, "Please Choose a State")){ if(lengthRestriction(username, 6, 8)){ if(emailValidator(email, "Please enter a valid email address")){ return true; } } } } } } return false; } function notEmpty(elem, helperMsg){ if(elem.value.length == 0){ alert(helperMsg); elem.focus(); // set the focus to this input return false; } return true; } function isNumeric(elem, helperMsg){ var numericExpression = /^[0-9]+$/; if(elem.value.match(numericExpression)){ return true; }else{ alert(helperMsg); elem.focus(); return false; } } function isAlphabet(elem, helperMsg){ var alphaExp = /^[a-zA-Z]+$/; if(elem.value.match(alphaExp)){ return true; }else{ alert(helperMsg); elem.focus(); return false; } } function isAlphanumeric(elem, helperMsg){ var alphaExp = /^[0-9a-zA-Z]+$/; if(elem.value.match(alphaExp)){ return true; }else{ alert(helperMsg); elem.focus(); return false; } } function lengthRestriction(elem, min, max){ var uInput = elem.value; if(uInput.length >= min && uInput.length <= max){ return true; }else{ alert("Please enter between " +min+ " and " +max+ " characters"); elem.focus(); return false; } } function madeSelection(elem, helperMsg){ if(elem.value == "Please Choose"){ alert(helperMsg); elem.focus(); return false; }else{ return true; } } function emailValidator(elem, helperMsg){ var emailExp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/; if(elem.value.match(emailExp)){ return true; }else{ alert(helperMsg); elem.focus(); return false; } } </script> Code (markup):
There are basically 2 ways. One is client side and the other server side. Client side (in browser) can be bypassed (javascript can be edited by end user and bypassed). To validate a form on the client side use, as in your example, Javascript and its libraries (jQuery makes it way more easy for example). And you validate inputs the way you want them. In HTML5 you can also add some tags like type="email" instead of text or required="required" .. but these can be bypassed. The server side check cannot be bypassed... unless someone hacks your server just to bypass that form xD.. This is done in PHP or whatever language your backend is made out of.
ok... form field = javascript variable javascript variable = function name function name does things isalphabet firstname isalphanumeric address isnumeric zip madeselection state lengthrestriction username emailvalidator email function isAlphabet(elem, helperMsg){ var alphaExp = /^[a-zA-Z]+$/; if(elem.value.match(alphaExp)){ return true; }else{ alert(helperMsg); elem.focus(); return false; } } Code (markup): <script type='text/javascript'> function formValidator(){ // Make quick references to our fields var firstname = document.getElementById('firstname'); var addr = document.getElementById('addr'); var zip = document.getElementById('zip'); var state = document.getElementById('state'); var username = document.getElementById('username'); var email = document.getElementById('email'); function notEmpty(elem, helperMsg){ if(elem.value.length == 0){ alert(helperMsg); elem.focus(); // set the focus to this input return false; } return true; } function isNumeric(elem, helperMsg){ var numericExpression = /^[0-9]+$/; if(elem.value.match(numericExpression)){ return true; }else{ alert(helperMsg); elem.focus(); return false; } } function isAlphabet(elem, helperMsg){ var alphaExp = /^[a-zA-Z]+$/; if(elem.value.match(alphaExp)){ return true; }else{ alert(helperMsg); elem.focus(); return false; } } function isAlphanumeric(elem, helperMsg){ var alphaExp = /^[0-9a-zA-Z]+$/; if(elem.value.match(alphaExp)){ return true; }else{ alert(helperMsg); elem.focus(); return false; } } function lengthRestriction(elem, min, max){ var uInput = elem.value; if(uInput.length >= min && uInput.length <= max){ return true; }else{ alert("Please enter between " +min+ " and " +max+ " characters"); elem.focus(); return false; } } function madeSelection(elem, helperMsg){ if(elem.value == "Please Choose"){ alert(helperMsg); elem.focus(); return false; }else{ return true; } } function emailValidator(elem, helperMsg){ var emailExp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/; if(elem.value.match(emailExp)){ return true; }else{ alert(helperMsg); elem.focus(); return false; } } // Check each input in the order that it appears in the form! if(isAlphabet(firstname, "Please enter only letters for your name")){ if(isAlphanumeric(addr, "Numbers and Letters Only for Address")){ if(isNumeric(zip, "Please enter a valid zip code")){ if(madeSelection(state, "Please Choose a State")){ if(lengthRestriction(username, 6, 8)){ if(emailValidator(email, "Please enter a valid email address")){ return true; } } } } } } return false; } </script> Code (markup): <script type='text/javascript'> function formValidator(){ // Make quick references to our fields var firstname = document.getElementById('firstname'); if(isAlphabet(firstname, "Please enter only letters for your name")){ function isAlphabet(elem, helperMsg){ var alphaExp = /^[a-zA-Z]+$/; if(elem.value.match(alphaExp)){ return true; }else{ alert(helperMsg); elem.focus(); return false; } } Code (markup):