为什么要用转义字符串?
HTML中< ,> ,& 等有特殊含义(< ,> ,用于链接标签,& 用于转义),不能直接使用。这些符号是不显示在我们最终看到的网页里的,那如果我们希望在网页中显示这些符号,该怎么办呢?
这就要说到 HTML转义字符串(Escape Sequence)了。
HTML转义字符串也称HTML字符实体(Character Entity)。在HTML中,定义转义字符串的原因有两个:第一个原因是像“< ”和“> ”这类符号已经用来表示 HTML 标签,因此就不能直接当作文本中的符号来使用。为了在 HTML 文档中使用这些符号,就需要定义它的转义字符串。当解释程序遇到这类字符串时就把它解释为真实的字符。在输入转义字符串时,要严格遵守字母大小写的规则。第二个原因是,有些字符在 ASCII 字符集中没有定义,因此需要使用转义字符串来表示。
转义字符串的组成
转义字符串分成三部分:第一部分是一个& 符号,英文叫 ampersand;第二部分是实体(Entity)名字或者是#加上实体(Entity)编号;第三部分是一个分号。
比如,要显示小于号(< ),就可以写 & lt; 或者 & #60; 。
用实体(Entity,区分大小写)名字的好处是比较好理解,一看 lt,大概就猜出是 less than 的意思,但是其劣势在于并不是所有的浏览器都支持最新的实体名字。而实体编号,各种浏览器都能处理。
同一个符号,可以用“实体名称”和“实体编号”两种方式引用,“实体名称”的优势在于便于记忆,但不能保证所有的浏览器都能顺利识别它,而“实体编号”则没有这种担忧,但它实在不方便记忆。
最常用的字符实体
显示 |
说明 |
实体名称 |
实体编号 |
---|---|---|---|
半方大的空白 |
& ensp; |
& #8194; |
|
全方大的空白 |
& emsp; |
& #8195; |
|
不断行的空白格 |
& nbsp; |
& #160; |
|
< |
小于 |
& lt; |
& #60; |
> |
大于 |
& gt; |
& #62; |
& |
& 符号 |
& amp; |
& #38; |
“ |
双引号 |
& quot; |
& #34; |
© |
版权 |
& copy; |
& #169; |
® |
已注册商标 |
& reg; |
& #174; |
™ |
商标(美国) |
& trade; |
& #8482; |
× |
乘号 |
& times; |
& #215; |
÷ |
除号 |
& divide; |
& #247; |
HTML特殊转义字符列表
显示 |
名称 |
编号 |
---|---|---|
& nbsp; |
& #160; |
|
¡ |
& iexcl; |
& #161; |
¢ |
& cent; |
& #162; |
£ |
& pound; |
& #163; |
¤ |
& curren; |
& #164; |
¥ |
& yen; |
& #165; |
¦ |
& brvbar; |
& #166; |
§ |
& sect; |
& #167; |
¨ |
& uml; |
& #168; |
© |
& copy; |
& #169; |
ª |
& ordf; |
& #170; |
« |
& laquo; |
& #171; |
¬ |
& not; |
& #172; |
|
& shy; |
& #173; |
® |
& reg; |
& #174; |
¯ |
& macr; |
& #175; |
° |
& deg; |
& #176; |
± |
& plusmn; |
& #177; |
² |
& sup2; |
& #178; |
³ |
& sup3; |
& #179; |
´ |
& acute; |
& #180; |
µ |
& micro; |
& #181; |
¶ |
& para; |
& #182; |
· |
& middot; |
& #183; |
¸ |
& cedil; |
& #184; |
¹ |
& sup1; |
& #185; |
º |
& ordm; |
& #186; |
» |
& raquo; |
& #187; |
¼ |
& frac14; |
& #188; |
½ |
& frac12; |
& #189; |
¾ |
& frac34; |
& #190; |
¿ |
& iquest; |
& #191; |
À |
& Agrave; |
& #192; |
Á |
& Aacute; |
& #193; |
 |
& Acirc; |
& #194; |
à |
& Atilde; |
& #195; |
Ä |
& Auml; |
& #196; |
Å |
& Aring; |
& #197; |
Æ |
& AElig; |
& #198; |
Ç |
& Ccedil; |
& #199; |
È |
& Egrave; |
& #200; |
É |
& Eacute; |
& #201; |
Ê |
& Ecirc; |
& #202; |
Ë |
& Euml; |
& #203; |
Ì |
& Igrave; |
& #204; |
Í |
& Iacute; |
& #205; |
Î |
& Icirc; |
& #206; |
Ï |
& Iuml; |
& #207; |
& Eth; |
& Eth; |
& #208; |
Ñ |
& Ntilde; |
& #209; |
Ò |
& Ograve; |
& #210; |
Ó |
& Oacute; |
& #211; |
Ô |
& Ocirc; |
& #212; |
Õ |
& Otilde; |
& #213; |
Ö |
& Ouml; |
& #214; |
× |
& times; |
& #215; |
Ø |
& Oslash; |
& #216; |
Ù |
& Ugrave; |
& #217; |
Ú |
& Uacute; |
& #218; |
Û |
& Ucirc; |
& #219; |
Ü |
& Uuml; |
& #220; |
Ý |
& Yacute; |
& #221; |
& thORN; |
& thORN; |
& #222; |
ß |
& szlig; |
& #223; |
à |
& agrave; |
& #224; |
á |
& aacute; |
& #225; |
â |
& acirc; |
& #226; |
ã |
& atilde; |
& #227; |
ä |
& auml; |
& #228; |
å |
& aring; |
& #229; |
æ |
& aelig; |
& #230; |
ç |
& ccedil; |
& #231; |
è |
& egrave; |
& #232; |
é |
& eacute; |
& #233; |
ê |
& ecirc; |
& #234; |
ë |
& euml; |
& #235; |
ì |
& igrave; |
& #236; |
í |
& iacute; |
& #237; |
î |
& icirc; |
& #238; |
ï |
& iuml; |
& #239; |
ð |
& eth; |
& #240; |
ñ |
& ntilde; |
& #241; |
ò |
& ograve; |
& #242; |
ó |
& oacute; |
& #243; |
ô |
& ocirc; |
& #244; |
õ |
& otilde; |
& #245; |
ö |
& ouml; |
& #246; |
÷ |
& divide; |
& #247; |
ø |
& oslash; |
& #248; |
ù |
& ugrave; |
& #249; |
ú |
& uacute; |
& #250; |
û |
& ucirc; |
& #251; |
ü |
& uuml; |
& #252; |
ý |
& yacute; |
& #253; |
þ |
& thorn; |
& #254; |
ÿ |
& yuml; |
& #255; |
数学和希腊字母标志
显示 |
名称 |
编号 |
---|---|---|
ƒ |
& fnof; |
& #402; |
Α |
& Alpha; |
& #913; |
Β |
& Beta; |
& #914; |
Γ |
& Gamma; |
& #915; |
Δ |
& Delta; |
& #916; |
Ε |
& Epsilon; |
& #917; |
Ζ |
& Zeta; |
& #918; |
Η |
& Eta; |
& #919; |
Θ |
& theta; |
& #920; |
Ι |
& Iota; |
& #921; |
Κ |
& Kappa; |
& #922; |
Λ |
& Lambda; |
& #923; |
Μ |
& Mu; |
& #924; |
Ν |
& Nu; |
& #925; |
Ξ |
& Xi; |
& #926; |
Ο |
& Omicron; |
& #927; |
Π |
& Pi; |
& #928; |
Ρ |
& Rho; |
& #929; |
Σ |
& Sigma; |
& #931; |
Τ |
& Tau; |
& #932; |
Υ |
& Upsilon; |
& #933; |
Φ |
& Phi; |
& #934; |
Χ |
& Chi; |
& #935; |
Ψ |
& Psi; |
& #936; |
Ω |
& Omega; |
& #937; |
α |
& alpha; |
& #945; |
β |
& beta; |
& #946; |
γ |
& gamma; |
& #947; |
δ |
& delta; |
& #948; |
ε |
& epsilon; |
& #949; |
ζ |
& zeta; |
& #950; |
η |
& eta; |
& #951; |
θ |
& theta; |
& #952; |
ι |
& iota; |
& #953; |
κ |
& kappa; |
& #954; |
λ |
& lambda; |
& #955; |
μ |
& mu; |
& #956; |
ν |
& nu; |
& #957; |
ξ |
& xi; |
& #958; |
ο |
& omicron; |
& #959; |
π |
& pi; |
& #960; |
ρ |
& rho; |
& #961; |
ς |
& sigmaf; |
& #962; |
σ |
& sigma; |
& #963; |
τ |
& tau; |
& #964; |
υ |
& upsilon; |
& #965; |
φ |
& phi; |
& #966; |
χ |
& chi; |
& #967; |
ψ |
& psi; |
& #968; |
ω |
& omega; |
& #969; |
? |
& thetasym; |
& #977; |
? |
& upsih; |
& #978; |
? |
& piv; |
& #982; |
• |
& bull; |
& #8226; |
… |
& hellip; |
& #8230; |
′ |
& prime; |
& #8242; |
″ |
& Prime; |
& #8243; |
‾ |
& oline; |
& #8254; |
⁄ |
& frasl; |
& #8260; |
℘ |
& weierp; |
& #8472; |
ℑ |
& image; |
& #8465; |
ℜ |
& real; |
& #8476; |
™ |
& trade; |
& #8482; |
ℵ |
& alefsym; |
& #8501; |
← |
& larr; |
& #8592; |
↑ |
& uarr; |
& #8593; |
→ |
& rarr; |
& #8594; |
↓ |
& darr; |
& #8595; |
↔ |
& harr; |
& #8596; |
↵ |
& crarr; |
& #8629; |
⇐ |
& lArr; |
& #8656; |
⇑ |
& uArr; |
& #8657; |
⇒ |
& rArr; |
& #8658; |
⇓ |
& dArr; |
& #8659; |
⇔ |
& hArr; |
& #8660; |
∀ |
& forall; |
& #8704; |
∂ |
& part; |
& #8706; |
∃ |
& exist; |
& #8707; |
∅ |
& empty; |
& #8709; |
∇ |
& nabla; |
& #8711; |
∈ |
& isin; |
& #8712; |
∉ |
& notin; |
& #8713; |
∋ |
& ni; |
& #8715; |
∏ |
& prod; |
& #8719; |
∑ |
& sum; |
& #8721; |
− |
& minus; |
& #8722; |
∗ |
& lowast; |
& #8727; |
√ |
& radic; |
& #8730; |
∝ |
& prop; |
& #8733; |
∞ |
& infin; |
& #8734; |
∠ |
& ang; |
& #8736; |
∧ |
& and; |
& #8743; |
∨ |
& or; |
& #8744; |
∩ |
& cap; |
& #8745; |
∪ |
& cup; |
& #8746; |
∫ |
& int; |
& #8747; |
∴ |
& there4; |
& #8756; |
∼ |
& sim; |
& #8764; |
∝ |
& cong; |
& #8773; |
≈ |
& asymp; |
& #8776; |
≠ |
& ne; |
& #8800; |
≡ |
& equiv; |
& #8801; |
≤ |
& le; |
& #8804; |
≥ |
& ge; |
& #8805; |
⊂ |
& sub; |
& #8834; |
⊃ |
& sup; |
& #8835; |
⊄ |
& nsub; |
& #8836; |
⊆ |
& sube; |
& #8838; |
⊇ |
& supe; |
& #8839; |
⊕ |
& oplus; |
& #8853; |
⊗ |
& otimes; |
& #8855; |
⊥ |
& perp; |
& #8869; |
⋅ |
& sdot; |
& #8901; |
? |
& lceil; |
& #8968; |
? |
& rceil; |
& #8969; |
? |
& lfloor; |
& #8970; |
? |
& rfloor; |
& #8971; |
? |
& lang; |
& #9001; |
? |
& rang; |
& #9002; |
◊ |
& loz; |
& #9674; |
& spades; |
& #9824; |
|
& clubs; |
& #9827; |
|
& hearts; |
& #9829; |
|
& diams; |
& #9830; |
重要的国际标记
显示 |
名称 |
编号 |
---|---|---|
“ |
& quot; |
& #34; |
& |
& amp; |
& #38; |
< |
& lt; |
& #60; |
> |
& gt; |
& #62; |
Œ |
& OElig; |
& #338; |
œ |
& oelig; |
& #339; |
Š |
& Scaron; |
& #352; |
š |
& scaron; |
& #353; |
Ÿ |
& Yuml; |
& #376; |
ˆ |
& circ; |
& #710; |
˜ |
& tilde; |
& #732; |
& ensp; |
& #8194; |
|
& emsp; |
& #8195; |
|
& thinsp; |
& #8201; |
|
|
& zwnj; |
& #8204; |
|
& zwj; |
& #8205; |
|
& lrm; |
& #8206; |
|
& rlm; |
& #8207; |
– |
& ndash; |
& #8211; |
— |
& mdash; |
& #8212; |
‘ |
& lsquo; |
& #8216; |
’ |
& rsquo; |
& #8217; |
‚ |
& sbquo; |
& #8218; |
“ |
& ldquo; |
& #8220; |
” |
& rdquo; |
& #8221; |
„ |
& bdquo; |
& #8222; |
† |
& dagger; |
& #8224; |
‡ |
& Dagger; |
& #8225; |
‰ |
& permil; |
& #8240; |
‹ |
& lsaquo; |
& #8249; |
› |
& rsaquo; |
& #8250; |
€ |
& euro; |
& #8364; |
JavaScript 转义符
转义序列 |
字符 |
---|---|
\b |
退格 |
\f |
走纸换页 |
\n |
换行 |
\r |
回车 |
\t |
横向跳格 (Ctrl-I) |
\’ |
单引号 |
\” |
双引号 |
\\ |
反斜杠 |
编程的时候要注意特殊字符的问题,很多运行时出现的问题都是因为特殊字符的出现而引起的。
注意,由于反斜杠本身用作转义符,因此不能直接在脚本中键入一个反斜杠。如果要产生一个反斜杠,必须一起键入两个反斜杠 (\\)。