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Pass PHP Variable To JavaScript And Use Alert To Display

I am attempting the below to pass the value in my php variable to JavaScript, but I never have the alert display on screen. What is the proper way to do such?
PHP
<?php $date = '20170101'; ?>
JavaScript
var datestring = <? php echo $date; ?>;
var year = datestring.substring(0,4);
alert(year);
Fiddle:
https://jsfiddle.net/3ed6opj3/
The desired result that I want to display in the alert is 2017 - the answers below to this point have all been showing <? p

You have to add " on between the php script
var datestring = "<?php echo $date; ?>";

You need to add quotes
<?php echo "\"".$date."\""; ?>;

how to convert strtotime in php to new Date in js

For a realtime countdown i use some php variables and echo them in the js like below:
$expire_year = '2016'; // year
$expire_month = '8'; // month ( 8 = August)
$expire_day = '14'; // day (14th)
$expire_hour = '2'; // hour ( 1-24)
$expire_minutes = '12'; // minutes
i use them in the js like blow:
timestamp = new Date(<?php echo $expire_year; ?>, <?php echo $expire_month - 1; ?>, <?php echo $expire_day; ?>, <?php echo $expire_hour; ?>, <?php echo $expire_minutes; ?>),
This works fine!
I use php strtotime to check if the date really has expired:
$quickpollexpiredate = strtotime("August 14, 2016 2:12"); // set an expiration date
So for the countdown timer in js and for the check in php, i have to use 2 different date "structures".
Is it possible to make a check in php so that i have to use only the 5 variables ($expire_year, $expire_month...) with strtotime() or another function?
So actually what i want to achieve is something like this (ofcourse this is wrong, but i hope you understand what i am trying to achieve)
$quickpollexpiredate = strtotime($expire_year, $expire_month, $expire_day, $expire_hour, $expire_minutes); // set an expiration date

If you have a timestamp in php, you can easily use it to set a Date object in javascript. You just need to consider that a timestamp in javascript is in milliseconds and not seconds like in php:
jsTimestamp = new Date(<?php echo $phpTimestamp; ?> * 1000);
or
jsTimestamp = new Date(<?php echo strtotime($yourDateString); ?> * 1000);
Note that new Date(...) also accepts strings, see https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Date for more details.

Using PHP inside a JavaScript function

I'm using the jQuery countdown plugin to have a timer on my website
http://keith-wood.name/countdownRef.html
I am using an API from SportsRadar to list some fixtures that has the dates on
<?php echo date("Y/d/m/ - H:i", strtotime($nextMatch['KickOff'])); ?>
this will output as 23/04/2015 - 20:00
In the Countdown plugin their function is the following
<script>
var matchDay = new Date();
matchDay = new Date(2015, 04-1, 22, 20, 0, 0);
</script>
I'm just looking to know how would I add that PHP echo into that JavaScript function? Is it even possible?

You an use something like:
var matchDay = new Date(<?php $time = strtotime($nextMatch['KickOff']);
echo date("Y", $time) . "," . date("m", $time) . "," .
date("m", $time) . "," . date("H", $time) . "," .
date("i", $time);
?>, 0, 0);
Or you an parse date in JavaScript

PHP function strtotime() gives you the number of seconds since 1970. You can use this information to initialize a javascript Date object. However, javascript expects the number of milliseconds since 1970, thus you ought to multiply the value by 1000:
<script>
var matchDay = new Date(<?php echo strtotime($nextMatch['KickOff'])*1000;?>);
</script>
Now you know when the match will take place (in javascript), and you can use it to initialize a countdown or whatever else you want to do with this information.

PHP is server-side and will run once. JS is much unlike this. If you need the JS to call a PHP script, consider making an AJAX call. Looking at your goals, however, this seems a tad unnecessary. If all you want is to echo data, you can use JS to update HTML elements on the page instead. That I believe would be the simple solution for your requirements.

By doing this it worked fine
<script>
var matchDay = new Date();
matchDay = new Date('<?php echo date("Y", strtotime($nextMatch['KickOff'])); ?>', '<?php echo date("m", strtotime($nextMatch['KickOff'])); ?>'-1, '<?php echo date("d", strtotime($nextMatch['KickOff'])); ?>', '<?php echo date("H", strtotime($nextMatch['KickOff'])); ?>','<?php echo date("i", strtotime($nextMatch['KickOff'])); ?>');
</script>

Unable to show php variable in javascript?

I am unable to show php variable in javascript;
this is my code here:
<script type="text/javascript">
$(document).ready(function (){
var n=<?php echo json_encode($count)?>;
for(var i=0;i<n;i++){
var div = document.createElement('div');
div.className = "d5";
div.id=i+1;
document.getElementById('wrapper').appendChild(div);
<?php
$query="select * from shop_product where shop_uniqueid='$unq'";
$result=mysql_query($query);
while($row=mysql_fetch_array($result))
{
$product=$row["in_product"];
?>
var product=<?php echo $product?>;
$('#'+div.id).html(product);
<?php
}
?>
}//for loop ends
});//ready ends
</script>
here i am trying to pass var product in html() of which value is coming from php like: var product=<?php echo $product?>;
but when doing so php value is not coming in Javascript's var product.
when I pass $('#'+div.id).html("abcd"); abcd value is showing in divs.
please help me.

Compare the first place you take data from PHP and put it in JavaScript:
var n=<?php echo json_encode($count)?>;
with your attempt to assign the product value:
var product=<?php echo $product?>;
You haven't converted the data from plain text to JavaScript in the second line. Use json_encode there too.

How to Pass Two Values From PHP to Ajax

Can you please let me know how I can pass Two Values from PHP file into a jQuery Ajax script. What I have is a Ajax call as:
<script>
$(function() {
var req = $.ajax({
url: 'captcha.php',
});
req.done(function(data){
alert(data);
})
});
</script>
and my PHP (captcha.php) is like:
<?php
$number1 = rand(1,9);
$number2 = rand(1,9);
$sum = $number1 + $number2;
echo $number1;
?>
as you can see currently I am able to pass the value of the $number1 but I need to have both values($number1 and $number2). Can you please let me know how to achieve this?
Thanks

Instead of sending (invalid) HTML to the client, use a structured data format, such as JSON.
<?php
header("Content-Type: application/json");
$data = Array($number1, $number2);
print json_encode($data);
exit;
In the JavaScript, jQuery will now populate data with an array.

Why don't you make an array containing variables to return and json_encode it to parse it in JS?
echo json_encode(array($number1, $number2));

Make an array out of your values:
$array = array($number1, $number2);
Then parse it to json
$json = json_encode($array);
Then echo out the $json and you have multiple variables in your js!

<script>
$(function() {
var req = $.ajax({
url: 'captcha.php',
});
req.done(function(data){
data = data.split(",");
//Number 1
alert(data[0]);
//Number 2
alert(data[1]);
})
});
</script>
<?php
$number1 = rand(1,9);
$number2 = rand(1,9);
$sum = $number1 + $number2;
echo $number1 .",". $number2;
?>
All this does is tells the php script to echo Number1,Number2 and then the javascript splits this string into an array from the ,

First Way
You can concatenate the two values seperating them by a special character like '_' like this
PHP
echo $number1 . '_' . $number2;
And then do like this in javascript
data = data.split('_'); // get an array with the two values
Second way
You can encode as JSON in php and do a json ajax request
PHP
$result = array($number1, $number2);
echo json_encode($result);
Javascript
$.getJSON('captcha.php',function(data){
console.log(data); //
});