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How do I pass variables and data from PHP to JavaScript?
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What is the easiest way to encode a PHP string for output to a JavaScript variable?
I have a PHP string which includes quotes and newlines. I need the contents of this string to be put into a JavaScript variable.
Normally, I would just construct my JavaScript in a PHP file, à la:
<script>
var myvar = "<?php echo $myVarValue;?>";
</script>
However, this doesn't work when $myVarValue contains quotes or newlines.
Expanding on someone else's answer:
<script>
var myvar = <?php echo json_encode($myVarValue); ?>;
</script>
Using json_encode() requires:
PHP 5.2.0 or greater
$myVarValue encoded as UTF-8 (or US-ASCII, of course)
Since UTF-8 supports full Unicode, it should be safe to convert on the fly.
Note that because json_encode escapes forward slashes, even a string that contains </script> will be escaped safely for printing with a script block.
encode it with JSON
function escapeJavaScriptText($string)
{
return str_replace("\n", '\n', str_replace('"', '\"', addcslashes(str_replace("\r", '', (string)$string), "\0..\37'\\")));
}
I have had a similar issue and understand that the following is the best solution:
<script>
var myvar = decodeURIComponent("<?php echo rawurlencode($myVarValue); ?>");
</script>
However, the link that micahwittman posted suggests that there are some minor encoding differences. PHP's rawurlencode() function is supposed to comply with RFC 1738, while there appear to have been no such effort with Javascript's decodeURIComponent().
The paranoid version: Escaping every single character.
function javascript_escape($str) {
$new_str = '';
$str_len = strlen($str);
for($i = 0; $i < $str_len; $i++) {
$new_str .= '\\x' . sprintf('%02x', ord(substr($str, $i, 1)));
}
return $new_str;
}
EDIT: The reason why json_encode() may not be appropriate is that sometimes, you need to prevent " to be generated, e.g.
<div onclick="alert(???)" />
<script>
var myVar = <?php echo json_encode($myVarValue); ?>;
</script>
or
<script>
var myVar = <?= json_encode($myVarValue) ?>;
</script>
Micah's solution below worked for me as the site I had to customise was not in UTF-8, so I could not use json; I'd vote it up but my rep isn't high enough.
function escapeJavaScriptText($string)
{
return str_replace("\n", '\n', str_replace('"', '\"', addcslashes(str_replace("\r", '', (string)$string), "\0..\37'\\")));
}
Don't run it though addslashes(); if you're in the context of the HTML page, the HTML parser can still see the </script> tag, even mid-string, and assume it's the end of the JavaScript:
<?php
$value = 'XXX</script><script>alert(document.cookie);</script>';
?>
<script type="text/javascript">
var foo = <?= json_encode($value) ?>; // Use this
var foo = '<?= addslashes($value) ?>'; // Avoid, allows XSS!
</script>
You can insert it into a hidden DIV, then assign the innerHTML of the DIV to your JavaScript variable. You don't have to worry about escaping anything. Just be sure not to put broken HTML in there.
You could try
<script type="text/javascript">
myvar = unescape('<?=rawurlencode($myvar)?>');
</script>
Don’t. Use Ajax, put it in data-* attributes in your HTML, or something else meaningful. Using inline scripts makes your pages bigger, and could be insecure or still allow users to ruin layout, unless…
… you make a safer function:
function inline_json_encode($obj) {
return str_replace('<!--', '<\!--', json_encode($obj));
}
htmlspecialchars
Description
string htmlspecialchars ( string $string [, int $quote_style [, string $charset [, bool $double_encode ]]] )
Certain characters have special significance in HTML, and should be represented by HTML entities if they are to preserve their meanings. This function returns a string with some of these conversions made; the translations made are those most useful for everyday web programming. If you require all HTML character entities to be translated, use htmlentities() instead.
This function is useful in preventing user-supplied text from containing HTML markup, such as in a message board or guest book application.
The translations performed are:
* '&' (ampersand) becomes '&'
* '"' (double quote) becomes '"' when ENT_NOQUOTES is not set.
* ''' (single quote) becomes ''' only when ENT_QUOTES is set.
* '<' (less than) becomes '<'
* '>' (greater than) becomes '>'
http://ca.php.net/htmlspecialchars
I'm not sure if this is bad practice or no, but my team and I have been using a mixed html, JS, and php solution. We start with the PHP string we want to pull into a JS variable, lets call it:
$someString
Next we use in-page hidden form elements, and have their value set as the string:
<form id="pagePhpVars" method="post">
<input type="hidden" name="phpString1" id="phpString1" value="'.$someString.'" />
</form>
Then its a simple matter of defining a JS var through document.getElementById:
<script type="text/javascript" charset="UTF-8">
var moonUnitAlpha = document.getElementById('phpString1').value;
</script>
Now you can use the JS variable "moonUnitAlpha" anywhere you want to grab that PHP string value.
This seems to work really well for us. We'll see if it holds up to heavy use.
If you use a templating engine to construct your HTML then you can fill it with what ever you want!
Check out XTemplates.
It's a nice, open source, lightweight, template engine.
Your HTML/JS there would look like this:
<script>
var myvar = {$MyVarValue};
</script>
I've used json_encode($array); to convert an array to a json.
[{"x":1418736600,"y":"82.2"},{"x":1418736900,"y":"82.2"}]
But what I really need is a JavaScript object like the following:
[{x:1418736600,y:"82.2"},{x:1418736900,y:"82.2"}]
To make it short I would like a JSON without quoting the keys, but it would be preferable avoiding parsing what json_encode outputs and using a more straightforward way instead.
Is it possible to do this in PHP?
Other than making the payload very slightly smaller, there's no need to do this. The output of json_encode is valid JavaScript code, if used where a value is expected, e.g.:
var x = <?php echo json_encode($array); ?>;
The quoted property keys are valid JavaScript. JSON as a whole is, in fact, a subset of JavaScript literal syntax.
You could throw a regular expression at the result. It can probably never be perfect (JSON, like HTML, can't be correctly parsed with a single regular expression), but within a limited domain you might be able to do it. For instance, here's a naive version that would probably work for many data sets, including your example, though again it would not work with all data sets by any means:
<?php
$str = json_encode($array);
$str = preg_replace('/"([A-Za-z0-9_$]+)":/', '$1:', $str);
?>
var x = <?php echo json_encode($array); ?>;
That assumes anything that consists of just A-Z, a-z, 0-9, _, or $ between double quotes followed immediately by a colon is a key and removes the quotes. (That's not a complete list of valid JavaScript identifier characters, it's just an example.)
But it seems unlikely to me that the savings are worth the bother.
To do it correctly, of course, you'd have to do your own serializer. It wouldn't be all that hard, just a recursive function that handles descending into arrays and objects. It could still use json_encode for the values.
I have seen that this question has been asked too many times over the years. Still can't refrain from asking if anything was improved during this time.
Currently, I have PHP code:
$jsonData = json_encode($data, JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_AMP | JSON_HEX_QUOT);
and then JS (Angular to be specific) comes into play:
var decoded = angular.fromJson('<?php echo $jsonData ; ?>');
The flags above do a very good job of keeping some of the issues at bay. However, given the example:
$data = ["name" => "Name \"Nickname\" Surname"];
JSON fails to parse. If I wrap the data with addslashes(), it does work, but then:
$data = ["name" => "Name 'Nickname' Surname"];
This fails.
Since the structure $data is highly unpredictable, and usually is 4-5 levels deep, my solution was:
array_walk_recursive($data, function(&$item, $key){
$item = str_replace('"', '\"', $item);
});
This works, however, I am looking for some more knowledgeable source. I've read some other SO questions where people escape not only double quotes but line feeds, carriage return and backslashes as well.
The last thing I need is to fall into edge case trap :)
Any hints for me?
Since json can be used directly as an object literal in javascript, you could use it like this:
var decoded = <?php echo $jsonData ; ?>;
thus eliminating the need to do any further parsing to avoid issues with ' or \ characters within the text. the json_encode should already be taking care of " charaters.
I encoded an array using json_encode() function and it gave me a string like this..
"[{"details":"power - 2000w \nac-220-240v \/ 50-60hz\n369 degree cordless base\n","model_id":"MC-EK3428 \/ MC-EK3328"}]"
as you can see it contains special characters like "\n"..I want these special characters to be replaced with "" because in javascript I am using the JSON.parse(); function to convert this string to an object..
but it gives me an error
syntaxerror : missing ) after argument list
I think this is because of the special characters in the string..how can I escape these?
Edit
php :
$view->jsonencoded_array = json_encode($array);
javascript :
var products = JSON.parse('<?php echo $jsonencoded_array; ?>');//this line gives me the error
update :
found out that the error is given in this :
'<?php echo $jsonencoded_array; ?>'
The problem here is that \n (and various other combinations) have special meaning inside a JavaScript string, and you are dumping your JSON into a JavaScript string without doing any conversion of those characters.
Since JSON is heavily inspired by JavaScript literal syntax, you can use json_encode to convert a PHP string into a JavaScript string.
There are some gotchas, the main one being that </script> can appear in a JSON text without causing any problems, but having that in the middle of your JavaScript <script> element is going to cause the HTML parser to cut off your JavaScript in the middle of the string … but PHP's default encoding rules will generate <\/script> which solves that problem.
So:
<?php
$json_array = json_encode($array);
$javascript_string = $json_encode($json_array);
?>
var products = JSON.parse(<?php echo $javascript_string; ?>);
That said. A JSON array is also a JavaScript array, so you can skip that step entirely.
<?php
$json_array = json_encode($array);
?>
var products = <?php echo $json_array; ?>;
There must something that you are missing or there is some other reason for your issue while parsing in JavaScript; because json_encode handles \n and other special characters such " \ etc. very well and escape them properly without any explicit work.
I would suggest you to check the JSON produced and you are supplying to JavaScript and see if there is something missing in between.
Note: You can do a str_replace but it is not advised. Better stick to json_encodesince its s standard function and it works well.
Edit:
You should be echoing $view->jsonencoded_array not just $jsonencoded_array, no need to parse already JSON object.
php :
$view->jsonencoded_array = json_encode($array);
javascript :
var products = <?php echo $view->jsonencoded_array; ?>;
json_encode() twice helped me to solve this issue..
$view->jsonencoded = json_encode(json_encode($array));
I need to do the following:
<?php
$userContentFromDatabase = 'Some string that may contain "double quotes" ';
?>
<script type="text/javascript">
var userContent = "<?= $userContentFromDatabase ?>";
</script>
How can I avoid the double quotes from interfering with the JavaScript code?
Use json_encode() on the PHP side and return an object as this will take care of all of the slashes and what not that might break your code.
Or just add slashes using str_replace() if you think that the only problem area will be the double quotes.
You need more escaping than that if you want to safely output user data in a javascript variable. See rule 3 https://www.owasp.org/index.php/XSS_(Cross_Site_Scripting)_Prevention_Cheat_Sheet#RULE_.233_-_JavaScript_Escape_Before_Inserting_Untrusted_Data_into_JavaScript_Data_Values