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Nick Thompson nick-thompson Clarify componentWillMount behavior542f20bCheng Lou chenglou docs fix back link in Examples6b15ad5Cheng Lou chenglou docs add jsx->js tab to live editors7ac5f3cPaul O’Shannessy zpao Normalize line endings6b1c6beBen Alpert spicyj Update homepage for new JSX/JS editor761e1c8Ben Alpert spicyj Properly clear live editor on JSX compile failured3fc5adBen Alpert spicyj Simplify live editor execution logicc7f0663Cheng Lou chenglou [docs] Tweak frontpage first example and jsx-compiler example8c8841cChristoph Pojer cpojer Update propTypes documentation.b66fbdeJean Lauliac jeanlauliac Update broken link in 'why react' article341d292Jean Lauliac jeanlauliac Normalize internal links in 'why react' article0681d13aymanosman aymanosman Fix typo09650e1Bob Eagan bobeagan fix incorrect link2edb76fBob Eagan bobeagan add hash link for lifecycle section of working with the browser page3db3460Pete Hunt petehunt remove references to react-page3120192Ben Alpert spicyj Fix docs typo6e4ddfdPaul O’Shannessy zpao Fix animation example code …dd66223Eric Schoffstall Contra fix grammar mistake64ac427Kunal Mehta kmeht Add documentation about React.renderComponent …f970453Christopher Chedeau vjeux s/Mock DOM/Virtual DOM/ …22772c9Ben Alpert spicyj Disable CodeMirror smart indentation …571d173Ben Alpert spicyj [docs] Fix comma splice3810c83
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<h1>JSX Gotchas</h1>
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<div class="subHeader"></div>
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<p>JSX looks like HTML but there are some important differences you may run into.</p>
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<blockquote>
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<p>Note:</p>
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<p>For DOM differences, such as the inline <code>style</code> attribute, check <a href="/react/docs/dom-differences.html">here</a>.</p>
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</blockquote>
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<h2><a class="anchor" name="whitespace-removal"></a>Whitespace Removal <a class="hash-link" href="#whitespace-removal">#</a></h2>
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<p>JSX doesn't follow the same whitespace elimination rules as HTML. JSX removes all whitespace between two curly braces expressions. If you want to have whitespace, simply add <code>{' '}</code>.</p>
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<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="o"><</span><span class="nx">div</span><span class="o">></span><span class="p">{</span><span class="k">this</span><span class="p">.</span><span class="nx">props</span><span class="p">.</span><span class="nx">name</span><span class="p">}</span> <span class="p">{</span><span class="s1">' '</span><span class="p">}</span> <span class="p">{</span><span class="k">this</span><span class="p">.</span><span class="nx">props</span><span class="p">.</span><span class="nx">surname</span><span class="p">}</span><span class="o"><</span><span class="err">/div></span>
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</code></pre></div>
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<p>Follow <a href="https://github.com/facebook/react/issues/65">Issue #65</a> for discussion on this behavior.</p>
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<h2><a class="anchor" name="html-entities"></a>HTML Entities <a class="hash-link" href="#html-entities">#</a></h2>
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<p>You can insert HTML entities within literal text in JSX:</p>
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<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="o"><</span><span class="nx">div</span><span class="o">></span><span class="nx">First</span> <span class="o">&</span><span class="nx">middot</span><span class="p">;</span> <span class="nx">Second</span><span class="o"><</span><span class="err">/div></span>
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</code></pre></div>
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<p>If you want to display an HTML entity within dynamic content, you will run into double escaping issues as React escapes all the strings you are displaying in order to prevent a wide range of XSS attacks by default.</p>
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<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="c1">// Bad: It displays "First &middot; Second"</span>
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<span class="o"><</span><span class="nx">div</span><span class="o">></span><span class="p">{</span><span class="s1">'First &middot; Second'</span><span class="p">}</span><span class="o"><</span><span class="err">/div></span>
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</code></pre></div>
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<p>There are various ways to work-around this issue. The easiest one is to write unicode character directly in Javascript. You need to make sure that the file is saved as UTF-8 and that the proper UTF-8 directives are set so the browser will display it correctly.</p>
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<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="o"><</span><span class="nx">div</span><span class="o">></span><span class="p">{</span><span class="s1">'First · Second'</span><span class="p">}</span><span class="o"><</span><span class="err">/div></span>
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</code></pre></div>
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<p>A safer alternative is to find the <a href="http://www.fileformat.info/info/unicode/char/b7/index.htm">unicode number corresponding to the entity</a> and use it inside of a JavaScript string.</p>
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<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="o"><</span><span class="nx">div</span><span class="o">></span><span class="p">{</span><span class="s1">'First \u00b7 Second'</span><span class="p">}</span><span class="o"><</span><span class="err">/div></span>
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<span class="o"><</span><span class="nx">div</span><span class="o">></span><span class="p">{</span><span class="s1">'First '</span> <span class="o">+</span> <span class="nb">String</span><span class="p">.</span><span class="nx">fromCharCode</span><span class="p">(</span><span class="mi">183</span><span class="p">)</span> <span class="o">+</span> <span class="s1">' Second'</span><span class="p">}</span><span class="o"><</span><span class="err">/div></span>
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</code></pre></div>
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<p>You can use mixed arrays with strings and JSX elements.</p>
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<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="o"><</span><span class="nx">div</span><span class="o">></span><span class="p">{[</span><span class="s1">'First '</span><span class="p">,</span> <span class="o"><</span><span class="nx">span</span><span class="o">>&</span><span class="nx">middot</span><span class="p">;</span><span class="o"><</span><span class="err">/span>, ' Second']}</div></span>
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</code></pre></div>
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<p>As a last resort, you always have the ability to insert raw HTML.</p>
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<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="o"><</span><span class="nx">div</span> <span class="nx">dangerouslySetInnerHTML</span><span class="o">=</span><span class="p">{{</span><span class="nx">__html</span><span class="o">:</span> <span class="s1">'First &middot; Second'</span><span class="p">}}</span> <span class="o">/></span>
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</code></pre></div><h2><a class="anchor" name="custom-html-attributes"></a>Custom HTML Attributes <a class="hash-link" href="#custom-html-attributes">#</a></h2>
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<p>If you pass properties to native HTML elements that do not exist in the HTML specification, React will not render them. If you want to use a custom attribute, you should prefix it with <code>data-</code>.</p>
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<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="o"><</span><span class="nx">div</span> <span class="nx">data</span><span class="o">-</span><span class="nx">custom</span><span class="o">-</span><span class="nx">attribute</span><span class="o">=</span><span class="s2">"foo"</span> <span class="o">/></span>
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</code></pre></div>
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<p><a href="http://www.w3.org/WAI/intro/aria">Web Accessibility</a> attributes starting with <code>aria-</code> will be rendered properly.</p>
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<div class="highlight"><pre><code class="javascript language-javascript" data-lang="javascript"><span class="o"><</span><span class="nx">div</span> <span class="nx">aria</span><span class="o">-</span><span class="nx">hidden</span><span class="o">=</span><span class="p">{</span><span class="kc">true</span><span class="p">}</span> <span class="o">/></span>
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</code></pre></div>
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