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I am trying to call JavaScript function with parameter that are PHP variables. I have tried 2 approaches.
calling JavaScript function in PHP with script tags in echo i.e
<?php
echo '<script>initialize('.$lat.','.$lang.','.$zom.');</script>';
?>
assigning PHP variables values to JavaScript variables
<script> var lat="<?php echo $lat;?>"; var lang="<?php echo $lang; ?>"; var zoom="<?php echo $zoom; ?>"; alert(lat+lang+zoom); initialize(lat,lang,zoom); </script>
In first case function is called as I cross-checked from page source but parameters passed are undefined. And in 2nd case values are successfully saved in JavaScript variables, check it by alert(), but function is not called.
Here is the whole code:
<!DOCTYPE html>
<html>
<head>
<script src="http://maps.googleapis.com/maps/api/js?key=AIzaSyDY0kkJiTPVd2U7aTOAwhc9ySH6oHxOIYM&sensor=false">
</script>
<?php
if( isset($_POST['lat']) && isset($_POST['lang']) && isset($_POST['zoom']) && isset($_POST['city'])):
$lat=$_POST['lat'];
$lang=$_POST['lang'];
$zoom=$_POST['zoom'];
$city=$_POST['city'];
$zom=(int)$zoom;
var_dump($lang);
var_dump($lat);
//var_dump($zoom);
var_dump($zom);
//echo '<script>initialize('.$lat.','.$lang.','.$zom.');</script>';
endif;
?>
<script>
var lat="<?php echo $lat; ?>";
var lang="<?php echo $lang; ?>";
var zoom="<?php echo $zoom; ?>";
alert(lat+lang+zoom);
initialize(lat,lang,zoom);
</script>
<script>
function initialize(a,b,zom){
if (!a || !b ||!zom){
alert('came on not' +a+b +zom);
// var centerLoc=new google.maps.LatLng( 33.61701054652337,73.37824736488983);
zoom=16;
}
else
{
alert('came');
var zoom =parseInt(zom);
var centerLoc=new google.maps.LatLng(a,b);
}
var mapProp = {
center:centerLoc,
zoom:zoom,
//mapTypeId:google.maps.MapTypeId.ROADMAP
mapTypeId:google.maps.MapTypeId.SATELLITE
};
var map=new google.maps.Map(document.getElementById("googleMap") ,mapProp);
marker=new google.maps.Marker({
position:centerLoc,
title:'Click to zoom'
});
google.maps.event.addListener(marker,'click',function() {
map.setZoom(map.getZoom()+1);
map.setCenter(marker.getPosition());
});
marker.setMap(map);
}
google.maps.event.addDomListener(window, 'load', initialize);
</script>
</head>
<body style= "background-color:gainsboro;">
<form method="POST" action="myPage.php" >
Enter latitude: <input type ="text" name="lat" id="lat" / ><br/>
Enter longitude: <input type ="text" name="lang" id="lang"/ ><br/>
Enter City Name: <input type="text" name="city" id="city"/><br/>
Enter Zoom level: <input type ="text" name="zoom" id="zoom"/ ><br/>
<input type="button" value ="Perview" onclick=" initialize(
document.getElementById('lat').value,
document.getElementById('lang').value,
document.getElementById('zoom').value)"/>
<input type="Submit" value="Save" />
</form>
<center><div id="googleMap" style="width:1000px;height:500px;"></div></center>
</body>
</html>
802
php if (isset($_SESSION['loggedin'])) {$login='t';}else{$login='f';} ?> <script> var login = "<? php echo $login ?>"; console. log(login); if (login == 'f'){ .. do something..}
You can execute Javascript through PHP by calling javascript code/function as a string in PHP and send it to the client browser to execute.
JavaScript is used as client side to check and verify client details and PHP is server side used to interact with database. In PHP, HTML is used as a string in the code. In order to render it to the browser, we produce JavaScript code as a string in the PHP code.
A JavaScript function does not perform any checking on parameter values (arguments).
Use json_encode(). If you don't there will always be the possibility you escaped your data incorrectly as it passes from the PHP to the HTML/JS layer.
$vars = array($lat, $lang, $zoom);
// JSON_HEX_TAG and JSON_HEX_AMP are to remove all possible surprises that could be
// caused by vars that contain '</script>' or '&' in them. The rules for
// escaping/encoding inside script elements are complex and vary depending
// on how the document is parsed.
$jsvars = json_encode($vars, JSON_HEX_TAG | JSON_HEX_AMP);
echo "<script>initialize.apply(null, $jsvars)</script>";
In general, for your sanity, all data that is in PHP that you need to make available to js running on the current page should be collected into a single PHP array and then placed into a single js object. For example:
<?php
$jsdata = array(
'formvars' => array(
'lat' => $lat,
'lang' => $lang,
'zoom' => $zoom
),
'username' => $username,
'some_other_data' => $more stuff
);
?>
<script>
var JSDATA = <?=json_encode($jsdata, JSON_HEX_TAG | JSON_HEX_AMP )?>;
initialize(JSDATA.formvars.lat, JSDATA.formvars.lang, JSDATA.formvars.zoom);
</script>
Now there is only a single point of contact between the JS and PHP/HTML layers so you can easily keep track of what you are putting into the JS namespace.
195
Call the function when the browser finished loading the javascript.
<script>
window.onload = function() {
var lat="<?php echo $lat; ?>";
var lang="<?php echo $lang; ?>";
var zoom="<?php echo $zoom; ?>";
alert(lat+lang+zoom);
initialize(lat,lang,zoom);
};
</script>
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