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JavaScript can be used to validate input data in HTML forms before sending off the content to a server.
JS可以用来校验HTML表单提交给服务器的数据(是否符合规范)
JavaScript can be used to validate input data in HTML forms before sending off the content to a server.
JS可以用来校验HTML表单提交给服务器的数据(老外就是喜欢重复)
Form data that typically are checked by a JavaScript could be:
典型的JS检查表单数据有以下:
The function below checks if a required field has been left empty. If the required field is blank, an alert box alerts a message and the function returns false. If a value is entered, the function returns true (means that data is OK):
下面的函数检查了必添的内容有没空掉。如果空了的话就会出现警告信息并返回false。如果写了内容那就返回true(意思就是数据没问题)
function validate_required(field,alerttxt) { with (field) { if (value==null||value=="") {alert(alerttxt);return false} else {return true} } } |
The entire script, with the HTML form could look something like this:
完整的脚本合起HTML表单:
<html> <head> <script type="text/javascript"> function validate_required(field,alerttxt) { with (field) { if (value==null||value=="") {alert(alerttxt);return false} else {return true} } } function validate_form(thisform) { with (thisform) { if (validate_required(email,"Email must be filled out!")==false) {email.focus();return false} } } </script> </head> <body> <form action="submitpage.htm" onsubmit="return validate_form(this)" method="post"> Email: <input type="text" name="email" size="30"> <input type="submit" value="Submit"> </form> </body> </html> |
The function below checks if the content has the general syntax of an email.
下面的函数会检查email内容的语法。
This means that the input data must contain at least an @ sign and a dot (.). Also, the @ must not be the first character of the email address, and the last dot must at least be one character after the @ sign:
意思就是输入的内容必须有起码一个@标记和一个点(.)而且@标记不能是email地址的第有个符号,点必须是在@标记后出现:
function validate_email(field,alerttxt) { with (field) { apos=value.indexOf("@") dotpos=value.lastIndexOf(".") if (apos<1||dotpos-apos<2) {alert(alerttxt);return false} else {return true} } } |
The entire script, with the HTML form could look something like this:
完整的样子是这样(加入了HTML表单):
<html> <head> <script type="text/javascript"> function validate_email(field,alerttxt) { with (field) { apos=value.indexOf("@") dotpos=value.lastIndexOf(".") if (apos<1||dotpos-apos<2) {alert(alerttxt);return false} else {return true} } } function validate_form(thisform) { with (thisform) { if (validate_email(email,"Not a valid e-mail address!")==false) {email.focus();return false} } } </script> </head> <body> <form action="submitpage.htm" onsubmit="return validate_form(this);" method="post"> Email: <input type="text" name="email" size="30"> <input type="submit" value="Submit"> </form> </body> </html> |