Rule symbol
| Regular classification | symbol | meaning | Remarks |
| Match position | ^ | beginning | |
| $ | end | ||
| Predefined | \d | 1 number | Simplification of commonly used character sets |
| \b | Word boundary | ||
| \w | 1 number or letter | ||
| \s | 1 empty character (space, line feed, tab) | ||
| . | Match all characters except carriage return and line feed | ||
| antonym | \D | Match any non-digit character | The letter is capitalized, and the meaning is opposite to the predefined. |
| \B | Match is not at the beginning or end of a word | ||
| \W | Match any character that is not a letter, number, or underscore | ||
| \S | Match any character that is not a whitespace | ||
| [^X] | Except X | Exclude, ^ can only be placed at the beginning. | |
| quantifier | {n,m} | At least n times, at most m times | The character set is written before the quantifier. The quantifier modifies the adjacent previous (left) character set. |
| {n,} | At least n times | ||
| {n} | Must be n times | ||
| ? | At most 1 time | ||
| * | Dispensable | ||
| + | At least once | ||
| Lazy qualifier | *? | Repeat as many times as possible, but as little as possible | Repeat as little as possible |
| +? | Repeat 1 or more times, but as little as possible | ||
| ?? | Repeat 0 or 1 times, but repeat as little as possible | ||
| {n,m}? | Repeat n to m times, but repeat as little as possible | ||
| {n,}? | Repeat more than n times, but repeat as little as possible | ||
| Shorthand | [A-Za-z] | 1 letter | The middle character is continuous and can be used-omit abbreviations. |
| [0-9] | 1 number | ||
| [\u4e00-\u9fa5] | 1 Chinese character | ||
| Escape character | \ | Make special characters into ordinary characters to be recognized, such as \+ | Tell the browser to escape the characters as the original text |
| select | Rule 1 | Rule 2 | or | Just satisfy one rule |
| Grouping | () | Wrap multiple character sets with () | In order to make a quantifier modify multiple character sets |
| (exp) | Match exp and capture the text into the automatically named group | Capture group | |
| (?<name>exp) | Match exp, and capture the text into the group named name | ||
| (?:exp) | Match exp, do not capture the matched text, nor assign a group number to this group | ||
| (?=exp) | Match the position before exp | ||
| (?<=exp) | Match the position behind exp | ||
| (?!exp) | Match the position that is not followed by exp | ||
| (?<!exp) | Match the position that is not exp before |
Common cases
| Common case | Rule description | Regular expression |
| identity number | The citizenship number is a characteristic combination code, which is composed of a 17-digit body code and a check code. The sequence from left to right is: six-digit address code, eight-digit date of birth code, three-digit sequence code and one-digit check code. | \d{15}(\d{2}[0-9xX])? |
| \d{17}[\d|x|X]|\d{15} | ||
| 手机号 | 11位手机号 | ^1[0-9]{10}$ |
| 11位手机号，约束第二位为 3 4 5 7 8 | ^1[34578]\d{9}$ | |
| 邮箱 | 邮箱不区分大小写 \w 匹配数字母下划线 中括号里是小写字母或0-9数字 后面+是一个或多个 转义一个点 任意多个字母 | /^\w+@[a-z0-9]+\.[a-z]+$/i |
| ^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$ | ||
| 密码 | 至少8字符 至少1大写字母 至少1小写字母 至少1数字字符 至少1特殊字符 | /^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[^\w\s]).{8,}$/ |
| 至少8-16个字符，至少1个大写字母，1个小写字母和1个数字，其他字符任意 | /^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)[^]{8,16}$/ | |
| 以字母开头，长度在6~18之间，只能包含字母、数字和下划线 | ^[a-zA-Z]\w{5,17}$ | |
| 必须包含大小写字母和数字的组合，不能使用特殊字符，长度在 8-10 之间 | ^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])[a-zA-Z0-9]{8,10}$ | |
| 必须包含大小写字母和数字的组合，可以使用特殊字符，长度在8-10之间 | ^(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{8,10}$ | |
| 域名 | [a-zA-Z0-9][-a-zA-Z0-9]{0,62}(\.[a-zA-Z0-9][-a-zA-Z0-9]{0,62})+\.? | |
| InternetURL | [a-zA-z]+://[^\s]* 或 ^http://([\w-]+\.)+[\w-]+(/[\w-./?%&=]*)?$ |