🧑🏾‍🤝‍🧑🏽 🚶 🎩 The character "f" is considered true in ng-show

<body>
  
  <header class="page-header js-page-header">
    <a class="page-header-logo-container" href="https://geek-questions.imtqy.com/index.html"></a>
    <div class="page-header-text">All geek questions in one place</div>
  </header>
  <section class="page js-page">
<div itemscope="" itemtype="http://schema.org/QAPage" class="page">

<div class="main-col" itemprop="mainEntity" itemscope="" itemtype="http://schema.org/Question">
<div class="question-header">
<h1 itemprop="name"><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">The character "f" is considered true in ng-show</font></font></h1>
</div>
<div class="question">
<div class="question-row">
<div class="question-text">
<div class="description" itemprop="text">
<p><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">When using angular, I had a very strange problem:</font></font></p>
<pre class="prettyprint-override"><code class="hljs xml"><span class="hljs-tag"><<span class="hljs-name">div</span> <span class="hljs-attr">ng-app</span>></span>
    <span class="hljs-tag"><<span class="hljs-name">textarea</span> <span class="hljs-attr">ng-model</span>=<span class="hljs-string">"resp"</span> <span class="hljs-attr">placeholder</span>=<span class="hljs-string">"Response"</span>></span><span class="hljs-tag"></<span class="hljs-name">textarea</span>></span>
    <span class="hljs-tag"><<span class="hljs-name">a</span> <span class="hljs-attr">ng-show</span>=<span class="hljs-string">"resp"</span>></span>Respond<span class="hljs-tag"></<span class="hljs-name">a</span>></span>
<span class="hljs-tag"></<span class="hljs-name">div</span>></span>
</code></pre>
<p> <a href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" rel="nofollow noreferrer"><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">Fiddle</font></font></a></p>
<p><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">When writing something in the text box, a link to the answer is displayed.</font></font></p>
<p><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">However, oddly enough, when writing the letter </font></font><strong><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">'f',</font></font></strong><font style="vertical-align: inherit;"><font style="vertical-align: inherit;"> the answer button is not displayed.</font></font></p>
<p><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">The workaround for this is to use the condition </font></font><code>resp.length>0</code><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">, but I wonder why the letter 'f' behaves in a special way.</font></font></p> </div>
<div class="favorite hidden"><i class="far fa-star"></i></div>
<div class="votes-question">
<i class="glyphicon glyphicon-arrow-ups"></i>
<div class="vote-count greenc" itemprop="upvoteCount"><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">
+4 </font></font></div>
<i class="glyphicon glyphicon-arrow-down"></i>
</div>
<div class="tags">
<a href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" class="tag" title="show questions tagged with 'angularjs'" rel="tag"><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">angularjs</font></font></a>
</div>
<div class="clearfix"></div>
<div class="action-time">
<span itemprop="author" itemscope="" itemtype="http://schema.org/Person"><span itemprop="name"><a href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" rel="noopener" target="_blank"><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">edi9999</font></font></a></span></span> <time title="2014-03-05 19:24" itemprop="dateCreated" datetime="2014-03-05T19:24:08+0000"><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">Mar 05 </font><font style="vertical-align: inherit;">'14 at 19:24</font></font></time>
</div>
<a class="aa-link" href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" target="_blank" rel="noopener"><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">source </font></font></a>
<a class="s-link" href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" title="share"><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">share</font></font></a>
<div class="clearfix"></div>
</div>
</div>
</div>
<ins style="height: 90px;display: block;" data-zxname="zx-adnet" data-zxadslot="ZX-QRST" data-zxw="0" data-zxh="90" data-zxid="2" data-overlay="false">

</ins>
<div class="answers " id="answers_hash">
<div class="answers-header">
<span class="pull-left"><span itemprop="answerCount"><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">4</font></font></span><font style="vertical-align: inherit;"><font style="vertical-align: inherit;"> answers</font></font></span>
<div class="clearfix"></div>
</div>
<div class="answer-pager hidden">
</div>
<div class="answer accepted" id="4626548_hash" itemscope="" itemtype="http://schema.org/Answer" itemprop="acceptedAnswer">
<div class="answer-row">
<div class="answer-text">
<div class="desc" itemprop="text">
<p><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">In fact, "f" counts </font></font><code>false</code><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">.</font></font></p>
<p><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">The AngularJS function uses an internal function </font></font><code>toBoolean</code><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">to evaluate </font></font><code>ng-show</code><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">/ </font><font style="vertical-align: inherit;">expressions </font></font><code>ng-hide</code><font style="vertical-align: inherit;"><font style="vertical-align: inherit;">.</font></font></p>
<p>       "f", "false", "0", "n", "no"  "[]".</p>
<p>     : <a href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" rel="nofollow noreferrer" src="">https://github.com/angular/angular.js/issues/1229</a>.</p>
<p>  angular <code>toBoolean</code>:</p>
<pre class="prettyprint-override"><code class="hljs cs"><span class="hljs-function">function <span class="hljs-title">toBoolean</span>(<span class="hljs-params"><span class="hljs-keyword">value</span></span>)</span> {
  <span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> <span class="hljs-keyword">value</span> === <span class="hljs-string">'function'</span>) {
    <span class="hljs-keyword">value</span> = <span class="hljs-literal">true</span>;<font></font>
  } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (<span class="hljs-keyword">value</span> && <span class="hljs-keyword">value</span>.length !== <span class="hljs-number">0</span>) {
    <span class="hljs-keyword">var</span> v = lowercase(<span class="hljs-string">""</span> + <span class="hljs-keyword">value</span>);
    <span class="hljs-keyword">value</span> = !(v == <span class="hljs-string">'f'</span> || v == <span class="hljs-string">'0'</span> || v == <span class="hljs-string">'false'</span> || v == <span class="hljs-string">'no'</span> || v == <span class="hljs-string">'n'</span> || v == <span class="hljs-string">'[]'</span>);<font></font>
  } <span class="hljs-keyword">else</span> {
    <span class="hljs-keyword">value</span> = <span class="hljs-literal">false</span>;<font></font>
  }<font></font>
  <span class="hljs-keyword">return</span> <span class="hljs-keyword">value</span>;<font></font>
}<font></font>
</code></pre>
<h2> :</h2>
<p> AngularJS 1.3+    .</p>
<p>: - <a href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" rel="nofollow noreferrer" src="">bdfc9c02</a>  'f', '0', 'false', 'no', 'n', '[]'     .   JavaScript,      , : false, null, undefined, NaN, 0  "".</p> </div>
<div class="votes-answer">
<i class="glyphicon glyphicon-arrow-ups"></i>
<div class="vote-count greenc" itemprop="upvoteCount">
+8 </div>
<i class="glyphicon glyphicon-arrow-down"></i>
</div>
<div class="clearfix"></div>
<div class="action-time">
<span itemprop="author" itemscope="" itemtype="http://schema.org/Person"><span itemprop="name"><a href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" rel="noopener" target="_blank">Alexandrin Rus</a></span></span> <time title="2014-03-05 19:29" itemprop="dateCreated" datetime="2014-03-05T19:29:04+0000"> 05 . '14  19:29</time>
</div>
<a class="aa-link" href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" target="_blank" rel="noopener"></a>
<a itemprop="url" class="s-link" href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" title="share"></a>
<div class="clearfix"></div>
</div>
</div>
</div>
<ins style="height: 90px;display: block;margin-top: 15px;" data-zxname="zx-adnet" data-zxadslot="ZX-QRST" data-zxw="0" data-zxh="90" data-zxid="3" data-overlay="false">

</ins>
<div class="answer rltd" id="4626551_hash" itemscope="" itemtype="http://schema.org/Answer" itemprop="suggestedAnswer">
<div class="answer-row">
<div class="answer-text">
<div class="desc" itemprop="text">
<p>  - ,   resp  .       ,    ,   .</p>
<pre class="prettyprint-override"><code class="hljs xml"><span class="hljs-tag"><<span class="hljs-name">div</span> <span class="hljs-attr">ng-app</span>></span>
    <span class="hljs-tag"><<span class="hljs-name">textarea</span> <span class="hljs-attr">ng-model</span>=<span class="hljs-string">"resp"</span> <span class="hljs-attr">placeholder</span>=<span class="hljs-string">"Response"</span>></span><span class="hljs-tag"></<span class="hljs-name">textarea</span>></span>
    <span class="hljs-tag"><<span class="hljs-name">a</span> <span class="hljs-attr">ng-show</span>=<span class="hljs-string">"resp != ''"</span>></span>Respond<span class="hljs-tag"></<span class="hljs-name">a</span>></span>
<span class="hljs-tag"></<span class="hljs-name">div</span>></span>
</code></pre> </div>
<div class="votes-answer">
<i class="glyphicon glyphicon-arrow-ups"></i>
<div class="vote-count greenc" itemprop="upvoteCount">
+1 </div>
<i class="glyphicon glyphicon-arrow-down"></i>
</div>
<div class="clearfix"></div>
<div class="action-time">
<span itemprop="author" itemscope="" itemtype="http://schema.org/Person"><span itemprop="name"><a href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" rel="noopener" target="_blank">BrightIntelDusk</a></span></span> <time title="2014-03-05 20:35" itemprop="dateCreated" datetime="2014-03-05T20:35:48+0000"> 05 . '14  20:35</time>
</div>
<a class="aa-link" href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" target="_blank" rel="noopener"></a>
<a itemprop="url" class="s-link" href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" title="share"></a>
<div class="clearfix"></div>
</div>
</div>
</div>

<div class="answer bt" id="4626549_hash" itemscope="" itemtype="http://schema.org/Answer" itemprop="suggestedAnswer">
<div class="answer-row">
<div class="answer-text">
<div class="desc" itemprop="text">
<p>   , <code>"f"</code>   <code>false</code>.  ,   :</p>
<pre class="prettyprint-override">"F"<font></font>
"false"<font></font>
"FALSE"<font></font>
"FaLsE"<font></font>
"  faLse "<font></font>
""<font></font>
" "<font></font>
"   "<font></font>
</pre>
<p>(..   /     )</p>
<p>   (, <code>"fa", "fal", "fals"</code>)  .</p> </div>
<div class="votes-answer">
<i class="glyphicon glyphicon-arrow-ups"></i>
<div class="vote-count " itemprop="upvoteCount">
0 </div>
<i class="glyphicon glyphicon-arrow-down"></i>
</div>
<div class="clearfix"></div>
<div class="action-time">
<span itemprop="author" itemscope="" itemtype="http://schema.org/Person"><span itemprop="name"><a href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" rel="noopener" target="_blank">jerry</a></span></span> <time title="2014-03-05 19:29" itemprop="dateCreated" datetime="2014-03-05T19:29:30+0000"> 05 . '14  19:29</time>
</div>
<a class="aa-link" href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" target="_blank" rel="noopener"></a>
<a itemprop="url" class="s-link" href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" title="share"></a>
<div class="clearfix"></div>
</div>
</div>
</div>
<div class="answer last" id="4626550_hash" itemscope="" itemtype="http://schema.org/Answer" itemprop="suggestedAnswer">
<div class="answer-row">
<div class="answer-text">
<div class="desc" itemprop="text">
<p>     . 'F', 'f', 'N', 'n', '0'      .     "".  "false"     "".</p> </div>
<div class="votes-answer">
<i class="glyphicon glyphicon-arrow-ups"></i>
<div class="vote-count " itemprop="upvoteCount">
0 </div>
<i class="glyphicon glyphicon-arrow-down"></i>
</div>
<div class="clearfix"></div>
<div class="action-time">
<span itemprop="author" itemscope="" itemtype="http://schema.org/Person"><span itemprop="name"><a href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" rel="noopener" target="_blank">user1927184</a></span></span> <time title="2014-03-05 19:32" itemprop="dateCreated" datetime="2014-03-05T19:32:02+0000"> 05 . '14  19:32</time>
</div>
<a class="aa-link" href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" target="_blank" rel="noopener"></a>
<a itemprop="url" class="s-link" href="https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=" title="share"></a>
<div class="clearfix"></div>
</div>
</div>
</div>
<div class="answer-pager hidden">
</div>
</div>

</div>
</div>
<p>Source: <a rel="nofollow" href="https://habr.com/ru/post/1530299/">https://habr.com/ru/post/1530299/</a></p>
<section class="more-articles-navigation-panel js-more-articles-navigation-panel">
<h4>More articles:</h4>
<nav class="list-of-articles-container js-list-of-articles-container"><ul class="list-of-pages js-list-of-pages">
<li><a href="../1530294/index.html">Longpolling effect on server - php</a></li>
<li><a href="../1530295/index.html">Find the maximum x, y value from a series of images - python</a></li>
<li><a href="../1530296/index.html">User defined and standard constructor? - java</a></li>
<li><a href="../1530297/index.html">выберите n-й файл в папке (с помощью sed)? - bash</a></li>
<li><a href="../1530298/index.html">How to identify / verify FaceTime contact information? - ios</a></li>
<li><a href="../1530300/index.html">Is there any way to show output during database update? - c #</a></li>
<li><a href="../1530301/index.html">PostgreSQL query dividing by zero error - sql</a></li>
<li><a href="../1530302/index.html">How to set up a legend with a certain height in highstock? - jquery</a></li>
<li><a href="../1530303/index.html">According to the standard, does std :: vector affect static order initialization problems? - c ++</a></li>
<li><a href="../1530304/index.html">https://translate.googleusercontent.com/translate_c?depth=1&pto=aue&rurl=translate.google.com&sl=ru&sp=nmt4&tl=en&u=https://fooobar.com/questions/1530304/restrict-access-to-the-admin-url-by-ip-in-django-with-nginx-and-gunicorn&usg=ALkJrhh3zppCo4QsgUMHWmHwnFGHS9ixJg</a></li>
</ul></nav>
</section><br />
<a href="../../allArticles.html"><strong>All Articles</strong></a>
<script src="../../js/main.js"></script>

<script type="text/javascript" >
  (function (d, w, c) {
      (w[c] = w[c] || []).push(function() {
          try {
              w.yaCounter62683636 = new Ya.Metrika({
                  id:62683636,
                  clickmap:true,
                  trackLinks:true,
                  accurateTrackBounce:true,
                  webvisor:true
              });
          } catch(e) { }
      });

var n = d.getElementsByTagName("script")[0],
          s = d.createElement("script"),
          f = function () { n.parentNode.insertBefore(s, n); };
      s.type = "text/javascript";
      s.async = true;
      s.src = "https://mc.yandex.ru/metrika/watch.js";

if (w.opera == "[object Opera]") {
          d.addEventListener("DOMContentLoaded", f, false);
      } else { f(); }
  })(document, window, "yandex_metrika_callbacks");
</script>
<noscript><div><img src="https://mc.yandex.ru/watch/62683636" style="position:absolute; left:-9999px;" alt="" /></div></noscript>

<script>
    window.ga = function () { ga.q.push(arguments) }; ga.q = []; ga.l = +new Date;
    ga('create', 'UA-166339405-1', 'auto'); ga('send', 'pageview')
  </script>
  <script src="https://www.google-analytics.com/analytics.js" async defer></script>

</section>

<footer class="page-footer">
  <div class="page-footer-legal-info-container page-footer-element">
    <p>
      Geek Questions | <span class="page-footer-legal-info-year js-page-footer-legal-info-year">2019</span>
    </p>
  </div>
  <div class="page-footer-counters-container page-footer-element">
    <a class="page-footer-counter-clustrmap" href='#'  title='Visit tracker'><img src='https://clustrmaps.com/map_v2.png?cl=698e5a&w=271&t=t&d=x9KFE5t3Mv44EqtuX_BNXcB69A0sIUZAkKxnezcia0Y&co=3a3a3a&ct=ffffff'/></a>
  </div>
</footer>
  
</body>

</html>