为什么onsubmit事件处理程序在php解释器中不起作用

Question

I am reading through Learning PHP, MySQL & Javascript 4th edition and in chapter 16 I encountered a problem. 我正在阅读学习PHP，MySQL和Javascript第4版，在第16章中遇到了一个问题。

Onsubmit event handler is not working in <?php ... ?> (PHP interpreter), while it is working just fine without it. Onsubmit事件处理程序无法在<?php ... ?> （PHP解释器）中运行，而没有它，则可以正常工作。 am I missing something? 我错过了什么吗？

I removed some parts of the code to just show the problem 我删除了部分代码只是为了显示问题

<?php
echo <<<_END
    <!DOCTYPE html>
        <html>
            <head>
                <title>An Example Form</title>
                <style>
                    .signup {
                        border:1px solid #999999;
                        font:  normal 14px helvetica;
                        color: #444444;
                    }    
                </style>
                <script>
                    function validate(form) {
                        fail  = validateForename(form.forename.value)

                        if(fail == "")   return true
                        else { alert(fail); return false }
                    }

                    function validateForename(field) {
                        return (field == "") ? "No Forename was entered.\n" : ""
                    }
                </script>
            </head>
            <body>
                <table border="0" cellpadding="2" cellspacing="5" bgcolor="#eeeeee">
                    <th colspan="2" align="center">Signup Form</th>
                    <form method="post" onsubmit="return validate(this)">
                        <tr><td>Forename</td>
                            <td><input type="text" maxlength="32" name="forename"></td>
                        </tr>
                        <tr><td colspan="2" align="center">
                            <input type="submit" value="Signup"></td>
                        </tr>
                    </form>
                </table>
            </body>
        </html>
_END;
?>

with this code in use, javascript alert function is not showing any alert even if I submit an empty form. 使用此代码后，即使我提交了一个空白表格，javascript警报功能也不会显示任何警报。

Here is just the HTML/CSS/JS: 这只是HTML / CSS / JS：

 <!DOCTYPE html> <html> <head> <title>An Example Form</title> <style> .signup { border: 1px solid #999999; font: normal 14px helvetica; color: #444444; } </style> <script> function validate(form) { fail = validateForename(form.forename.value) if (fail == "") return true else { alert(fail); return false } } function validateForename(field) { return (field == "") ? "No Forename was entered.\\n" : "" } </script> </head> <body> <table border="0" cellpadding="2" cellspacing="5" bgcolor="#eeeeee"> <th colspan="2" align="center">Signup Form</th> <form method="post" onsubmit="return validate(this)"> <tr> <td>Forename</td> <td><input type="text" maxlength="32" name="forename"></td> </tr> <tr> <td colspan="2" align="center"> <input type="submit" value="Signup"></td> </tr> </form> </table> </body> </html>

Answer 1

您必须两次对换行符\\n进行转义，否则HTML输出将不符合预期：

return (field == "") ? "No Forename was entered.\\n" : ""

为什么onsubmit事件处理程序在php解释器中不起作用

问题描述

1 个解决方案

解决方案1
2 已采纳 2019-05-25 18:46:09

为什么onsubmit事件处理程序在php解释器中不起作用

问题描述

1 个解决方案

解决方案1 2 已采纳 2019-05-25 18:46:09

解决方案1
2 已采纳 2019-05-25 18:46:09