20150209--js consolidation and strengthening 6-02

Source: Internet
Author: User

Seven , writing regular Expressions Tips : Regular write a three-step walk: 1 ) check what? 2) check how much? 3) where to find out? 1. Regular An expression consists of:

Regular expressions are text patterns that consist of ordinary characters, such as characters A through z, and special characters (called metacharacters). A regular expression, as a template, matches a character pattern to the string you are searching for. 2 , check how much? (Meta -character-qualifier )

Qualifiers can specify how many times a given component of a regular expression must appear to satisfy a match.

* Match previous sub-expression 0 or more times (0 to more)

+ Match Previous sub-expression one or more times (1 to many)

? Match the preceding subexpression 0 or one time (0 or 1)

{n} matches determined n times

{N,} matches at least n times {4,} minimum match 4 times

{n,m} matches at least n times and matches M-Times {3,7}

Example code:

Example 1: Matching a continuous 11-digit number

Example 2: Match character ABC occurs in a string of 0 or 1 times

Example 3: Query numeric characters appear at least 4 times in a string

Example 4: Query text character (A-Z) string occurrences in 3, 7

3. Matching principle: 1) greedy match

In regular expressions, we call this greedy match when we match as many as possible. (Default principle) 2) non- greedy match

In regular expressions, you can pass the? Question mark to change our greedy matching principle, we call this principle non-greedy matching principle

Example code: plus? After that, will be separated by 3 times, less than 3 times, will omit

Do not add? , matches a number of 3-9 characters and separates it by a group of 9

4. Check what (meta-character--match )

Character matches are used to match one or some characters

What we call a character cluster in a regular expression that is enclosed in parentheses

l [A-z]: matches any character in a-Z

l [A-z]: matches any character in a-Z

l [0-9]: Match any number in the 0-9 \d

l [0-9a-z]: matches any character in 0-9 or A-Z

l [0-9a-za-z]: matches any character in 0-9 or A-Z or a-Z

l [ABCD]: match character A or character B or character C or character D

l [1234]: match the number 1 or the number 2 or the number 3 or the number 4

In the regular expression of the character cluster, you can use the upper key ^ ^ to take the inverse

l [^a-z]: match any character except A-Z

l [^0-9]: matches any character except 0-9 \d

l [^ABCD]: match any character except the letter Abcd

L \d: matches a numeric character [0-9]

L \d: Matches a non-numeric character [^0-9]

L \w: matches any word character that includes an underscore [0-9a-za-z_]

L \w: matches any non-word character [^\w]

L \s: matches any white space character spaces, tab stop, etc.

L \s: matches any non-whitespace character [^\s]

L. : matches any single character except "\ n"

Sample code

Example 1: Match any numeric character

Example 2: Match any of the characters in a ASW three character

Example 3: Match all the spaces

Example 4: Matching three consecutive uppercase letters

Example 5: Matching Chinese characters

5. from where to check ( Meta character --Locator)

A locator can pin a regular expression to the beginning or end of a line. You can also create a regular expression that appears only within a word or only at the beginning or end of a word.

Example 1: Matching 11-digit phone number

Example 2: Matching a fixed phone

020-87654321 38 Structure

0451-7654321 47 Structure

^\d{3}-\d{8}$

^\d{4}-\d{7}$

^\d{4}-\d{8}$

^: Top Gear (start position)

$: End Position

\b: Represents the word boundary position

\b: Represents a non-word boundary

Example 3: Word Boundaries and non-word boundaries

6. Special Characters

1) escape character

In regular expressions, \ is used to match certain special characters

/ + * ? ( ) [] {} . ^ $ \

Example code:

Example 1: match [left symbol]

Example 2: Match the. number in the URL

Example 3: Matching by character cluster. No.

7 , Selection Character

In regular expressions, you can represent selectors by |

Example 1: Matching Hellojavascript or hellophp

8. three special uses

(? =): Forward pre-check

(?!) : Negative pre-check (reverse pre-check)

(?:): output content without capturing 1) forward pre-check

2) negative to pre-check

3) output but not capture

Eight , regular expression--stutter program

Stutter Program

I... Yes, I am. A ... Handsome handsome handsome ... Brother! ";

Turn

I am a handsome guy!

Example code:

Description

Solution:

1) first remove all the. Numbers from the string to replace with the null character

2) match all repeated characters to the original content by sub-expression and put in a buffer

3) In the Replace method, the second argument, you can use $n (a positive integer of n>=1&&n<=99) to refer to the contents of the N-number buffer. Nine , writing Regular Toolbox

Code please refer to tools.html 10 , Job summary

Zuoye01.html

Zuoye02.html

...

Zuoye04.html

snake.html 11 , Operation

Mailbox Verification

rxy @itcast . CN

IP authentication

192.168.114.10

0-223 First place

0-255 after three digits

20150209--js consolidation and strengthening 6-02

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