lgorithm to convert a pair of UTF-16 code units into a
Unicode code point, adapted from the [ Unicode FAQ
](https://unicode.org/faq/utf_bom.html#utf16-3) :

js

    
    
    // constants
    const LEAD_OFFSET = 0xd800 - (0x10000 >> 10);
    const SURROGATE_OFFSET = 0x10000 - (0xd800 << 10) - 0xdc00;
    
    function utf16ToUnicode(lead, trail) {
      return (lead << 10) + trail + SURROGATE_OFFSET;
    }
    function unicodeToUTF16(codePoint) {
      const lead = LEAD_OFFSET + (codePoint >> 10);
      const trail = 0xdc00 + (codePoint & 0x3ff);
      return [lead, trail];
    }
    
    const str = "ð ®·";
    console.log(utf16ToUnicode(str.charCodeAt(0), str.charCodeAt(1))); // 134071
    console.log(str.codePointAt(0)); // 134071
    

##  Specifications

Specification  
---  
[ ECMAScript Language Specification  
#  sec-string.prototype.charcodeat  ](https://tc39.es/ecma262/multipage/text-
processing.html#sec-string.prototype.charcodeat)  
  
##  Browser compatibility

BCD tables only load in the browser  with JavaScript enabled. Enable
JavaScript to view data.

##  See also

  * [ ` String.fromCharCode() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/fromCharCode)
  * [ ` String.prototype.charAt() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/charAt)
  * [ ` String.fromCodePoint() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/fromCodePoint)
  * [ ` String.prototype.codePointAt() ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/codePointAt)

##  Help improve MDN

Was this page helpful to you?

Yes  No

[ Learn how to contribute
](https://github.com/mdn/content/blob/main/CONTRIBUTING.md "This will take you
to our contribution guidelines on GitHub.") .

This page was last modified on  Jul 3, 2023  by  [ MDN contributors ](/en-
US/docs/Web/JavaScript/Reference/Global_Objects/String/charCodeAt/contributors.txt)
.

[ View this page on GitHub
](https://github.com/mdn/content/blob/main/files/en-
us/web/javascript/reference/global_objects/string/charcodeat/index.md?plain=1
"Folder: en-us/web/javascript/reference/global_objects/string/charcodeat
\(Opens in a new tab\)") â¢  [ Report a problem with this content
](https://github.com/mdn/content/issues/new?template=page-report.yml&mdn-
url=https%3A%2F%2Fdeveloper.mozilla.org%2Fen-
US%2Fdocs%2FWeb%2FJavaScript%2FReference%2FGlobal_Objects%2FString%2FcharCodeAt&metadata=%3C%21--+Do+not+make+changes+below+this+line+--%3E%0A%3Cdetails%3E%0A%3Csummary%3EPage+report+details%3C%2Fsummary%3E%0A%0A*+Folder%3A+%60en-
us%2Fweb%2Fjavascript%2Freference%2Fglobal_objects%2Fstring%2Fcharcodeat%60%0A*+MDN+URL%3A+https%3A%2F%2Fdeveloper.mozilla.org%2Fen-
US%2Fdocs%2FWeb%2FJavaScript%2FReference%2FGlobal_Objects%2FString%2FcharCodeAt%0A*+GitHub+URL%3A+https%3A%2F%2Fgithub.com%2Fmdn%2Fcontent%2Fblob%2Fmain%2Ffiles%2Fen-
us%2Fweb%2Fjavascript%2Freference%2Fglobal_objects%2Fstring%2Fcharcodeat%2Findex.md%0A*+Last+commit%3A+https%3A%2F%2Fgithub.com%2Fmdn%2Fcontent%2Fcommit%2Fa49d60648404407784b04ff5ff7e16a6a8d1ac25%0A*+Document+last+modified%3A+2023-07-03T09%3A41%3A03.000Z%0A%0A%3C%2Fdetails%3E
"This will take you to GitHub to file a new issue.")

[ MDN logo  ](/)

Your blueprint for a better internet.

  * [ MDN on Mastodon  ](https://mozilla.social/@mdn)
  * [ MDN on X (formerly Twitter)  ](https://twitter.com/mozdevnet)
  * [ MDN on GitHub  ](https://github.com/mdn/)
  * [ MDN Blog RSS Feed  ](/en-US/blog/rss.xml)

##  MDN

  * [ About ](/en-US/about)
  * [ Blog ](/en-US/blog/)
  * [ Careers ](https://www.mozilla.org/en-US/careers/listings/?team=ProdOps)
  * [ Advertise with us ](/en-US/advertising)

##  Support

  * [ Product help ](https://support.mozilla.org/products/mdn-plus)
  * [ Report an issue ](/en-US/docs/MDN/Community/Issues)

##  Our communities

  * [ MDN Community ](/en-US/community)
  * [ MDN Forum ](https://discourse.mozilla.org/c/mdn/236)
  * [ MDN Chat ](/discord)

##  Developers

  * [ Web Technologies ](/en-US/docs/Web