您可以使用函数html_entity_decode()和²的HTML实体代码²。
您的代码看起来如下所示：

<meta charset="utf-8">

<script>
    document.write(encodeURIComponent(';<?php echo html_entity_decode("&sup2;") ?>'));
</script>

您可以使用urlencode()函数：

echo urlencode(';²');

上述函数输出%3B%C2%B2。

谢谢！我的IDE将文件编码从UTF-8恢复为ANSI，但仍然正确显示 ²。如果文件以UTF-8保存，输出是相同的。

您没有说明使用了哪个PHP函数，但我建议

urlencode()

• 但是 * 你应该记住，有一些小的区别。在http://phpjs.org/functions/urlencode/的家伙做了一个JavaScript等效于phpencode：

function urlencode(str) {
  //       discuss at: http://phpjs.org/functions/urlencode/
  //      original by: Philip Peterson
  //      improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  //      improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  //      improved by: Brett Zamir (http://brett-zamir.me)
  //      improved by: Lars Fischer
  //         input by: AJ
  //         input by: travc
  //         input by: Brett Zamir (http://brett-zamir.me)
  //         input by: Ratheous
  //      bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  //      bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  //      bugfixed by: Joris
  // reimplemented by: Brett Zamir (http://brett-zamir.me)
  // reimplemented by: Brett Zamir (http://brett-zamir.me)
  //             note: This reflects PHP 5.3/6.0+ behavior
  //             note: Please be aware that this function expects to encode into UTF-8 encoded strings, as found on
  //             note: pages served as UTF-8
  //        example 1: urlencode('Kevin van Zonneveld!');
  //        returns 1: 'Kevin+van+Zonneveld%21'
  //        example 2: urlencode('http://kevin.vanzonneveld.net/');
  //        returns 2: 'http%3A%2F%2Fkevin.vanzonneveld.net%2F'
  //        example 3: urlencode('http://www.google.nl/search?q=php.js&ie=utf-8&oe=utf-8&aq=t&rls=com.ubuntu:en-US:unofficial&client=firefox-a');
  //        returns 3: 'http%3A%2F%2Fwww.google.nl%2Fsearch%3Fq%3Dphp.js%26ie%3Dutf-8%26oe%3Dutf-8%26aq%3Dt%26rls%3Dcom.ubuntu%3Aen-US%3Aunofficial%26client%3Dfirefox-a'

  str = (str + '')
    .toString();

  // Tilde should be allowed unescaped in future versions of PHP (as reflected below), but if you want to reflect current
  // PHP behavior, you would need to add ".replace(/~/g, '%7E');" to the following.
  return encodeURIComponent(str)
    .replace(/!/g,   '%21')
    .replace(/'/g,   '%27')
    .replace(/\(/g,  '%28')
    .replace(/\)/g,  '%29')
    .replace(/\*/g,  '%2A')
    .replace(/%20/g, '+');
}