Passing value from javascript to PHP ( Hidden Field )

Question

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Can you please give me example of passing value from javascript to PHP through hidden field?
Thanks.

I'm trying to pass the value from body.php

HTML

<html>
<head><script type="text/javascript" src="../js/script.js"></script</head>
<body>
<form name="myform" method="post"
 önSubmit="return validateRadio()" action="">

<table class="tftable" border="1">
<tr><th><div align="center" class="tftable th">Questions</div></th><th colspan="2"><div align="center">Answer</div></th>
</tr>
<tr>
  <td>I like to dance</td>
  <td>
  <label></label>
  <label>
  <input name="bm1" type="radio" value="1" />
  Yes</label>
</td>
<td>
<label></label>
<label>
<input name="bm1" type="radio" value="2" />
No
</label>
</td></table></form>

<?php
if (isset($_GET['myval']))
{
echo "VALUE PASSED  : ".$_GET['myval']."<br>";
}
?>
</body>
</html>

Here's script.js

JavaScript

function validateRadio()
{
// get all the inputs type
var inputs = myform.elements;
var radios = [];

// find the radio type
for (var i = 0; i < inputs.length; ++i) {
if (inputs[i].type == 'radio') {
radios.push(inputs[i]);
}
}
var countChecked = 0;
for (var j = 0; j < radios.length; j++) {
if (radios[j].checked) {
countChecked++;
}
}
//count number of radio button with value=1
var answeramount = 0;
for (var k = 0; k < radios.length; k++){
if(radios[k].checked && radios[k].value==1){
answeramount++;
}
}
if (countChecked != radios.length / 2){
alert("All questions must be answered.");
return false; // abort submit
} else {
 window.location.href = "body.php?myval=" + answeramount;
return true; // proceed to submit
} 
}

The echo "VALUE PASSED : ".$_GET['myval'] doesn't work...
Please help...

Posted 13-Apr-14 8:18am

monsterchub

Updated 13-Apr-14 8:50am

v4

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Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) 13-Apr-14 14:25pm

What have you tried?

monsterchub 13-Apr-14 14:51pm

I've improve the question above.. thx

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ) 13-Apr-14 15:00pm

Good. :)

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Sergey Alexandrovich Kryukov · Accepted Answer · 2014-04-13T09:39:00

You are doing it wrong. Your myVal is not a part of the body of HTTP request; it is a part of the URL.

With PHP, you can get the URL of the request as $_SERVER['QUERY_STRING'].
Then you can use the PHP function parse_str, to parse it to an array:
http://php.net/manual/en/function.parse-str.php[^].

Passing parameters through the UTR string is not a very elegant way. If you want to pass some values via the HTTP request, say, through the methods "GET" or "POST" you can:

Have a Wen form with the method (form attribute) "post" or "get", with the input controls representing data to be posted; the names of the parameters defined by the values of the values of the attribute name of those controls.
Using form is not an universal method; and it needs reloading of the whole page. It's main benefit is: it does not require Javascript.

The alternative method is using Ajax:
http://en.wikipedia.org/wiki/Ajax_%28programming%29[^],
https://api.jquery.com/jQuery.ajax[^].

Good luck.

—SA

monsterchub · Accepted Answer · 2014-04-14T05:21:00

I tried some solution, so I have changed the some code. Still got error undefined variable. What did i miss?
This is body.php, I add the hidden field and submit button.

HTML

<html>
<head><script type="text/javascript" src="../js/script.js"></script>br mode="hold" /><body>
<form name="myform" method="post">
 önSubmit="return validateRadio()" action="check.php">
 
<table class="tftable" border="1">
<tr><th><div align="center" class="tftable th">Questions</div></th><th colspan="2"><div align="center">Answer</div></th>
</tr>
<tr>
  <td>I like to dance</td>
  <td>
  <label></label>
  <label>
  <input name="bm1" type="radio" value="1" />
  Yes</label>
</td>
<td>
<label></label>
<label>
<input name="bm1" type="radio" value="2" />
No
</label>
</td></tr></table>
<input type="submit" name="submit" id="submit" value="Next">
<input type="hidden" name="passvalue" id="passvalue" value="echo $passvalue;">
</input></input></form>
</body></head></html>

And the script.js , I add document.getElementsById

JavaScript

function validateRadio()
{
// get all the inputs type
var inputs = myform.elements;
var radios = [];

// find the radio type
for (var i = 0; i < inputs.length; ++i) {
if (inputs[i].type == 'radio') {
radios.push(inputs[i]);
}
}
var countChecked = 0;
for (var j = 0; j < radios.length; j++) {
if (radios[j].checked) {
countChecked++;
}
}
//count number of radio button with value=1
var answeramount = 0;
for (var k = 0; k < radios.length; k++){
if(radios[k].checked && radios[k].value==1){
answeramount++;
}
}
if (countChecked != radios.length / 2){
alert("All questions must be answered.");
return false; // abort submit
} else {
document.getElementsById('passvalue').Value = answeramount;
return true; // proceed to submit
} 
}

I add check.php to print the passvalue

PHP

<?php $passvalue=$_POST['passvalue'];
echo $passvalue;
?>

Passing value from javascript to PHP ( Hidden Field )

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