How do I escape only single quotes?
Quite simply: echo str_replace('\'', '\\\'', $myString);However, I'd suggest use of JSON and json_encode() function as it will be more reliable (quotes new lines for instance):
<?php $data = array('myString' => '...'); ?><script> var phpData = <?php echo json_encode($data) ?>; alert(phpData.myString);</script>
If you want to escape characters with a \, you have addcslashes(). For example, if you want to escape only single quotes like the question, you can do:
echo addcslashes($value, "'");And if you want to escape ', ", \, and nul (the byte null), you can use addslashes():
echo addslashes($value);