How Can I Safely Pass a PHP String to a JavaScript Variable, Handling Special Characters?

Passing PHP Variable to JavaScript Variable with String Encoding

When dealing with PHP strings containing special characters, like quotes or newlines, it becomes challenging to output them directly into JavaScript variables. To overcome this, we need to encode the PHP string before passing it.

One effective solution is to use the json_encode() function:

<script>
  var myvar = <?= json_encode($myVarValue, JSON_UNESCAPED_UNICODE); ?>;
</script>

Here's how it works:

• json_encode() converts the PHP value into a JSON string.
• By specifying JSON_UNESCAPED_UNICODE, Unicode characters are preserved without escaping, ensuring that special characters are passed intact.

Requirements:

• PHP 5.2.0 or later
• PHP string encoded in UTF-8 (or US-ASCII)

Caution:

• When using json_encode() in HTML attributes (e.g., onclick), pass its result through htmlspecialchars():

htmlspecialchars(json_encode($string), ENT_QUOTES);

This prevents potential issues with HTML entities such as "&bar;" being misinterpreted within JavaScript code.

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