PHP & Javascript 如何对字符串中包含html标签进行编码 整理

为什么要对字符串编码？

某些字符串中包含html标签，不编码，页面输出就乱了。

PHP下怎么对字符串编码？

htmlentities
vs htmlspecialchars

htmlentities 与htmlspecialchar 区别：

htmlentities is
identical to htmlspecialchars() in
all ways, except with htmlentities(),
all characters which have HTML character entity equivalents are translated into these entities.

除了不加参数直接调用htmlentities()以外，这2个function是等价的。

不加参数直接调用htmlentities()时，会把输入的字符串全部当作html标签去编码，所以会产生乱码。

htmlspecialchars只处理这几种字符：

'&' (ampersand) becomes '&'
'"' (double quote) becomes '"' when

ENT_NOQUOTES

is
not set.
"'" (single quote) becomes ''' (or ') only when

ENT_QUOTES

is
set.
'<' (less than) becomes '<'
'>' (greater than) becomes '>'

都支持同样的编码参数：

ENT_COMPAT	Will convert double-quotes and leave single-quotes alone.
ENT_QUOTES	Will convert both double and single quotes.
ENT_NOQUOTES	Will leave both double and single quotes unconverted.
ENT_IGNORE	Silently discard invalid code unit sequences instead of returning an empty string. Using this flag is discouraged as it » may have security implications.
ENT_SUBSTITUTE	Replace invalid code unit sequences with a Unicode Replacement Character U+FFFD (UTF-8) or &#FFFD; (otherwise) instead of returning an empty string.
ENT_DISALLOWED	Replace invalid code points for the given document type with a Unicode Replacement Character U+FFFD (UTF-8) or &#FFFD; (otherwise) instead of leaving them as is. This may be useful, for instance, to ensure the well-formedness of XML documents with embedded external content.
ENT_HTML401	Handle code as HTML 4.01.
ENT_XML1	Handle code as XML 1.
ENT_XHTML	Handle code as XHTML.
ENT_HTML5	Handle code as HTML 5.

参考：点击打开链接http://php.net/manual/zh/function.htmlentities.php

点击打开链接http://php.net/manual/zh/function.htmlspecialchars.php

javascript 中怎么对字符串编码？

js中只有 encodeURI()，encodeURIComponent()，escape()

前两个只对uri编码，后一个编码范围太大

参考： 点击打开链接http://www.w3school.com.cn/jsref/jsref_encodeURIComponent.asp

点击打开链接http://www.w3school.com.cn/jsref/jsref_encodeURIComponent.asp

为什么要对URI编码？

参考：/article/4863818.html点击打开链接

js中如何对包含html标签字符串编码，一般做法：

function html_encode(str) {
var s = "";
if (str.length == 0) return "";
s = str.replace(/&/g, ">");
s = s.replace(/</g, "<");
s = s.replace(/>/g, ">");
s = s.replace(/ /g, " ");
s = s.replace(/\'/g, "'");
s = s.replace(/\"/g, """);
s = s.replace(/\n/g, "<br>");
return s;
}