javascript variable not reading php variable

Question

in the script below the javascript variable (date) is not displaying the value of the php variable (field). Php variable is the info that i need to pass to another page.

If I dont use if (isset($_POST['submit'])) and set $field="something"; then it works. What am I doing wrong?

Thanks in anticipation for the help

<HTML>
<BODY>

<?php 
if (isset($_POST['submit'])) {$field = $_POST['field'];}
?>

<FORM name="filter" METHOD ="POST" ACTION ="">

<select name="filteroptions" onChange="chgAction()">

<option value="" selected="selected">select an option</option>

<option value="Date Range" <?php if(isset($_POST['filteroptions']) && $_POST['filteroptions'] == 'Date Range') echo 'selected= "selected"'; ?>>Date Range</option>

</select> 

<input type="text" name="field">

<INPUT TYPE = "submit" name="submit">

</form>


 <script>

function chgAction() {

var date = "<?php echo "/log/date.php?id=".$field; ?>";

        var form = document.filter;

    console.log('chgAction()');
    console.log(form.filteroptions.selectedIndex);

    switch (form.filteroptions.selectedIndex) {
        case 1:
            form.action = date;
            break;
           }

} 

</script>

</BODY>
</HTML>

Answer 1

The $_POST will only contain data after the the data has been submitted. And your code can only work if the data is posted back to this page.

So if a user who has not submitted data to this page, has just loaded this page. Then it will not work. The $field will not exist because there is no post array value "submit".

If a user is either on this page or another page, that posts data to this page & within that post data contains the fields: 'submit' & 'field' then it'll work.

Answer 2

As in this PHP Fiddle , if field is set and submitted already you'll get the log for the corresponding date, if field is not defined it will complain

<?php 
    if(isset($_POST['submit'])){
        $field = $_POST['field'];
    }else{
        $field = '';
    }
?>
<form name="filter" method="POST" action="">
    <select name="filteroptions" onChange="chgAction()">
        <option value="" selected="selected">select an option</option>
        <option value="Date Range" <?php if(isset($_POST['filteroptions']) && $_POST['filteroptions'] == 'Date Range') echo 'selected= "selected"'; ?>>Date Range</option>
    </select>
    <input type="text" name="field">
    <input type = "submit" name="submit">
</form>
<script>
    function chgAction() {
        var field = "<?php echo $field; ?>";
        if(field != ''){
            var date = "/log/date.php?id=" + field;
            alert(date);
        }
        else{
            alert('Please select a date range');
        }
    }
</script>

javascript variable not reading php variable

Question

2 answers

solution1
0 ACCPTED 2015-11-16 00:05:15

solution2
0 2015-11-16 00:32:51

javascript variable not reading php variable

Question

2 answers

solution1 0 ACCPTED 2015-11-16 00:05:15

solution2 0 2015-11-16 00:32:51

solution1
0 ACCPTED 2015-11-16 00:05:15

solution2
0 2015-11-16 00:32:51