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copied!<blockquote> <p>In js you have to double-escape a dot/character to get an escaped char.</p> </blockquote> <p>You don't get an "escaped char". You get two characters, a backslash and a dot. The dot is not "escaped."</p> <p>The sequence <code>\.</code> is not special in JavaScript string literals. Any escape sequence other than <a href="http://www.ecma-international.org/ecma-262/5.1/#sec-7.8.4" rel="nofollow">the ones defined by the spec</a> just silently drop the escape character.</p> <p>Your example <code>"\." == "."</code> is <code>true</code> because both literals define the same string, which has <em>one</em> character (a dot). The invalid escape is ignored.</p> <p>Your example <code>"\\." == "."</code> is <code>false</code> because the first literal defines a string with two characters in it (a backslash and a dot), the second defines a string with only one character in it (a dot).</p> <p>How different languages respond to invalid escape sequences varies by language. Some, like JavaScript, just ignore the invalid escape. Others treat an invalid escape sequence as a backslash followed by the next character, e.g., they silently escape the backslash rather than silently dropping the escape.</p> <hr> <p>Re your regex example:</p> <blockquote> <p>In js regexes it works other way around, how weird :)</p> <pre><code>"\.".search(/\./) // no hit <--- Wrong "\\.".search(/\./) // hit </code></pre> </blockquote> <p>That's incorrect, the first one hits as well (the return value for "no match" is <code>-1</code>, not <code>0</code>). The return value of <code>"\.".search(/\./)</code> is <code>0</code> (found a match at index 0, which makes sense, because the <code>.</code> is the first character). The return value of <code>"\\.".search(/\./)</code> is <code>1</code> (found a match at index 1, which makes sense, because the <code>.</code> is the <em>second</em> character).</p> <p>And of course, it's quite correct that you escaped the <code>.</code> in the regular expression literal, because <code>.</code> <strong>is</strong> special in JavaScript regular expressions.</p>

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