Html & 用于什么
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What is & used for
提问by blue-sky
Is there any difference in behaviour of below URL.
以下 URL 的行为是否有任何差异。
I don't know why the &is inserted, does it make any difference ?
我不知道为什么&插入，这有什么区别吗？
www.testurl.com/test?param1=test&current=true
versus
相对
www.testurl.com/test?param1=test¤t=true
回答by Quentin
&is HTML for "Start of a character reference".
&是“字符引用的开始”的 HTML。
&is the character reference for "An ampersand".
&是“和号”的字符参考。
¤t;is not a standard character reference and so is an error (browsers may try to perform error recovery but you should not depend on this).
¤t;不是标准字符引用，因此是错误（浏览器可能会尝试执行错误恢复，但您不应依赖于此）。
If you used a character reference for a real character (e.g. ™) then it (™) would appear in the URL instead of the string you wanted.
如果您对真实字符使用了字符引用（例如™），那么它 (™) 将出现在 URL 中，而不是您想要的字符串中。
(Note that depending on the version of HTML you use, you may have to end a character reference with a ;, which is why &trade=will be treated as ™. HTML 4 allows it to be ommited if the next character is a non-word character (such as =) but some browsers (Hello Internet Explorer) have issues with this).
（请注意，根据您使用的 HTML 版本，您可能必须以 结束字符引用;，这就是&trade=将被视为 ™ 的原因。如果下一个字符是非单词字符，HTML 4 允许省略它（例如=），但某些浏览器（您好 Internet Explorer）对此有问题）。
回答by Samjus
HTML doesn't recognize the &but it will recognize &because it is equal to &in HTML
HTML 不能识别，&但它会识别，&因为它等于&HTML
I looked over this post someone had made: http://www.webmasterworld.com/forum21/8851.htm
我查看了某人发表的这篇文章：http: //www.webmasterworld.com/forum21/8851.htm
回答by Jim
My Source: http://htmlhelp.com/tools/validator/problems.html#amp
我的来源：http: //htmlhelp.com/tools/validator/problems.html#amp
Another common error occurs when including a URL which contains an ampersand ("&"):
包含一个包含与号 ("&") 的 URL 时会发生另一个常见错误：
This is invalid:
这是无效的：
a href="foo.cgi?chapter=1§ion=2©=3&lang=en"
a href="foo.cgi?chapter=1§ion=2©=3&lang=en"
Explanation:
解释：
This example generates an error for "unknown entity section" because the
"&"is assumed to begin an entity reference. Browsers often recover safely from this kind of error, but real problems do occur in some cases. In this example, many browsers correctly convert ©=3 to ?=3, which may cause the link to fail. Since ⟨ is the HTML entity for the left-pointing angle bracket, some browsers also convert &lang=en to 〈=en. And one old browser even finds the entity §, converting §ion=2 to §ion=2.
此示例为“未知实体部分”生成错误，因为
"&"假定它开始实体引用。浏览器通常会从这种错误中安全地恢复，但在某些情况下确实会出现真正的问题。在这个例子中，许多浏览器正确地将 ©=3 转换为 ?=3，这可能会导致链接失败。由于 ⟨ 是左指尖括号的 HTML 实体，因此一些浏览器还将 &lang=en 转换为 ⟨=en。一个旧浏览器甚至找到实体 §，将 §ion=2 转换为 §ion=2。
So the goal here is to avoid problems when you are trying to validate your website. So you should be replacing your ampersands with &when writing a URL in your markup.
因此，这里的目标是在您尝试验证网站时避免出现问题。因此，&在您的标记中编写 URL 时，您应该将您的 & 号替换为 。
Note that replacing
&with& is only done when writing the URL in HTML, where"&"is a special character (along with "<" and ">"). When writing the same URL in a plain text email message or in the location bar of your browser, you would use"&"and not"&". With HTML, the browser translates"&"to"&"so the Web server would only see"&"and not"&"in the query string of the request.
请注意，替换
&为& 仅在以 HTML 编写 URL 时完成，其中"&"是特殊字符（以及“<”和“>”）。在纯文本电子邮件或浏览器的地址栏中写入相同的 URL 时，您将使用"&"而不是"&"。使用 HTML 时，浏览器会转换"&"为"&"Web 服务器只会看到"&"而不是"&"在请求的查询字符串中。
Hope this helps : )
希望这可以帮助 ： ）
回答by Alohci
That a great example. When ¤tis parsed into a text nodeit is converted to ¤t. When parsed into an attribute value, it is parsed as ¤t.
这是一个很好的例子。当¤t被解析为文本节点时，它被转换为¤t. 当解析为一个属性值时，它被解析为¤t.
If you want ¤tin a text node, you should write &currentin your markup.
如果你想要¤t一个文本节点，你应该写&current在你的标记中。
The gory details are here: http://dev.w3.org/html5/spec/tokenization.html#consume-a-character-reference
血腥细节在这里：http: //dev.w3.org/html5/spec/tokenization.html#consume-a-character-reference
回答by Urbanek Krzysztof
if you're doing a string of characters. make:
如果你正在做一串字符。制作：
let linkGoogle = 'https://www.google.com/maps/dir/?api=1';
let origin = '&origin=' + locations[0][1] + ',' + locations[0][2];
aNav.href = linkGoogle + origin;
