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class="docMainContainer_sTIZ"><div class="container padding-top--md padding-bottom--lg"><div class="row"><div class="col docItemCol_Qr34"><div class="docItemContainer_tjFy"><article><nav class="theme-doc-breadcrumbs breadcrumbsContainer_T5ub" aria-label="Breadcrumbs"><ul class="breadcrumbs" itemscope="" itemtype="https://schema.org/BreadcrumbList"><li class="breadcrumbs__item"><a aria-label="Home page" class="breadcrumbs__link" href="/devicescript/"><svg viewBox="0 0 24 24" class="breadcrumbHomeIcon_sfvy"><path d="M10 19v-5h4v5c0 .55.45 1 1 1h3c.55 0 1-.45 1-1v-7h1.7c.46 0 .68-.57.33-.87L12.67 3.6c-.38-.34-.96-.34-1.34 0l-8.36 7.53c-.34.3-.13.87.33.87H5v7c0 .55.45 1 1 1h3c.55 0 1-.45 1-1z" fill="currentColor"></path></svg></a></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item"><a class="breadcrumbs__link" itemprop="item" href="/devicescript/language"><span itemprop="name">Language Reference</span></a><meta itemprop="position" content="1"></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item breadcrumbs__item--active"><span class="breadcrumbs__link" itemprop="name">Strings and Unicode</span><meta itemprop="position" content="2"></li></ul></nav><div class="theme-doc-markdown markdown"><h1>Strings and Unicode</h1><p>ECMAScript spec requires <code>String.charCodeAt()</code> to return a 16-bit value.
Unicode code points outside of 16-bit (mostly emoticons, but also some historical alphabets,
and rare Chinese/Japanese/Korean ideograms) are represented as surrogate pairs of two 16-bit code units.
The <code>String.length</code> returns the number of UTF-16 code units in the string.</p><p>If ES was designed today they would probably return up to 21-bit values from <code>charCodeAt()</code>,
or possibly use yet another abstraction since even with full 21-bit Unicode,
several code points can still combine into a single glyph (character displayed on the screen). </p><p>In DeviceScript,
the method <code>String.charCodeAt()</code> returns Unicode code point (up to 21 bits), not UTF-16 character.
Similarly, <code>String.length</code> will return the number of 21-bit code points.
Thus, <code>"🗽".length === 1</code> and <code>"🗽".charCodeAt(0) === 0x1f5fd</code>,
and also <code>"\uD83D\uDDFD".length === 1</code> since <code>"\uD83D\uDDFD" === "🗽"</code> which may be confusing.</p><p>Also string <a href="https://github.com/microsoft/devicescript/issues/39" target="_blank" rel="noopener noreferrer">construction by concatnation quadratic</a>,
however you can use <code>String.join()</code> which is linear in the size of output.</p><p>See also <a href="https://github.com/microsoft/devicescript/discussions/34" target="_blank" rel="noopener noreferrer">discussion</a>.</p></div></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages"><a class="pagination-nav__link pagination-nav__link--prev" href="/devicescript/language/tostring"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">toString() method</div></a><a class="pagination-nav__link pagination-nav__link--next" href="/devicescript/language/special"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">Special objects</div></a></nav></div></div></div></div></main></div></div><footer class="footer footer--dark"><div class="container container-fluid"><div class="row footer__links"><div class="col footer__col"><div class="footer__title">Docs</div><ul class="footer__items clean-list"><li class="footer__item"><a class="footer__link-item" href="/devicescript/intro">Introduction</a></li><li class="footer__item"><a class="footer__link-item" href="/devicescript/developer">Developer</a></li><li class="footer__item"><a class="footer__link-item" href="/devicescript/language">Language Reference</a></li><li class="footer__item"><a class="footer__link-item" href="/devicescript/api/cli">API</a></li></ul></div><div class="col footer__col"><div class="footer__title">Info</div><ul class="footer__items clean-list"><li class="footer__item"><a href="https://github.com/microsoft/devicescript/" target="_blank" rel="noopener noreferrer" class="footer__link-item">GitHub<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPrP"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://github.com/microsoft/devicescript/discussions" target="_blank" rel="noopener noreferrer" class="footer__link-item">Discussions<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPrP"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://go.microsoft.com/fwlink/?linkid=2259814" target="_blank" rel="noopener noreferrer" class="footer__link-item">Consumer Health Privacy<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPrP"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li></ul></div><div class="col footer__col"><div class="footer__title">Legal</div><ul class="footer__items clean-list"><li class="footer__item"><a href="https://go.microsoft.com/fwlink/?LinkId=521839" target="_blank" rel="noopener noreferrer" class="footer__link-item">Privacy & Cookies<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPrP"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://www.microsoft.com/en-us/legal/intellectualproperty/copyright" target="_blank" rel="noopener noreferrer" class="footer__link-item">Terms of Use<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPrP"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li><li class="footer__item"><a href="https://www.microsoft.com/en-us/legal/intellectualproperty/trademarks/usage/general" target="_blank" rel="noopener noreferrer" class="footer__link-item">Trademarks<svg width="13.5" height="13.5" aria-hidden="true" viewBox="0 0 24 24" class="iconExternalLink_nPrP"><path fill="currentColor" d="M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z"></path></svg></a></li></ul></div></div><div class="footer__bottom text--center"><div class="footer__copyright">Copyright © 2024 Microsoft Corporation.</div></div></div></footer></div>
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