Try testing the following form with valid and invalid email addresses. The code uses javascript to match the users input with a regular expression. 函数代码：
复制代码 代码如下:
function validate(form_id,email) { var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/; var address = document.forms[form_id].elements[email].value; if(reg.test(address) == false) { alert('Invalid Email Address'); return false; } }
In the forms ‘onsubmit' code call javascript:return validate(‘form_id','email_field_id') 使用方法：
You should not rely purely on client side validation on your website / web application, if the user has javascript disabled this will not work. Always validate on the server. from: http://www.white-hat-web-design.co.uk/blog/javascript-validation/
