How Can I Safely Pass PHP Variables to JavaScript Variables?

Passing PHP Variables to JavaScript Variables

When working with dynamic web pages, it often becomes necessary to pass data from a PHP script into a JavaScript variable. This can be a challenging process, especially when the PHP variable contains special characters such as quotes or newlines.

One straightforward approach is to use the echo statement within a PHP string to directly insert the variable into the JavaScript code, as shown below:

<script>
  var myvar = "<?php echo $myVarValue; ?>";
</script>

However, this method can lead to errors if the PHP variable contains characters that are not valid in JavaScript, such as quotes or newlines. To avoid this issue, it is recommended to use the json_encode() function from PHP. This function converts the PHP variable into a JSON string, which can then be safely passed to a JavaScript variable.

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

The json_encode() function must be used within a PHP echo statement to output the converted value. It requires PHP version 5.2.0 or later and expects the PHP variable to be encoded in UTF-8 format.

This technique allows you to seamlessly pass PHP variables into JavaScript variables, even when the PHP variable contains special characters.

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