Summary of JS Regular expressions

When you need to pass a parameter, you must use the new RegExp ();

var re = new RegExp (' \\b ' +sclass+ ' \\b ');

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Quantifier, escape character:

\s: Space
\s: Non-whitespace

\d: Digital
\d: Non-digital

\w: Characters (Letters, numbers, underscores)
\w: Non-character

\. : The real point

\b: Separate section (Start, end, space)
\b: A non-independent part

^: Put in front of the regular, represent the beginning
$: End of Representative

/^[1-9]\d{4,11}$///QQ Detection

+: appears at least once;
| : OR
^: non-[in brackets inside the meaning of right and wrong]
. : Any character

{}:
{4,7}: Minimum 4 times, maximum 7 times
{4,}: At least 4 times, no Limit
{4}: exactly 4 times

+:{1,} that appears at least 1 times
?: {0,1} occurs 0 or 1 times
*:{0,} that appears at least 0 times

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Identity: Case insensitive I global match g

The regular default is case-sensitive,
If case insensitive, Mark I at the end of the regular;
The regular match succeeds and the match is not continued.
If you want to find all, Mark G;(Global match at the end of the regular)

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Four common methods of test search match replace

1, regular. Test (string) [Match succeeded: return True, failed: return FALSE]
2, String. Search (regular) [match succeeded: return position, Failure: return-1]
3, String. Match (regular) [Match succeeded: Returns the matching successful array, failed: return NULL]
4, String. Replace (regular, second argument)
Replace the second argument can be a [string],
It can also be a [callback function], the first parameter of the function is the character that matches the success,
String. replace (regular, function ($0,$1,$2) {})

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Match subkey: Parentheses ()
[Group Operations]

String. replace (regular, function ($0,$1,$2) {})
$: Mother; (overall)
$: first child; (first parenthesis)
$: Second child; (second parenthesis)

var str = ' abc ';
var re=/(a) (b) (c)/;
Str.match (re); Back to [Abc,a,b,c]
Match only has no G (global match) to get children

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Character classes: A set of similar elements
[] The whole of the brackets represents one character

var str= ' abc ';

var re=/a[bde]c/;

Alert (Re.test (str)); Returns True

var str= ' ABDC ';

var re=/a[bde]c/;

Alert (Re.test (str)); Returns false

var str= ' abc ';

var re=/a[a-z0-9a-z]c/;

Alert (Re.test (str));

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\b: Separate section (Start, end, space)

var str= ' Onetwo ';

var re=/\bone/; True

var re=/one\b/; False

Alert (Re.test (str));

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Repeating children

\1: Duplicate First subkey
\2: Duplicate Second subkey

var str = ' ABCA ';
var re =/(a) (b) (c) \1/; True
var re =/(a) (b) (c) \2/; False

Alert (Re.test (str));

var re =/\w\w/; C9
var re =/(\w) \1/; CC 99

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Find the most frequently occurring characters and times

var str= ' Ahlihkhkjsssssssssssssdasdasdasdasdsdafafqrghjff ';

var arr = Str.split ("); Split array

Str=arr.sort (). Join (');//Array string

var re=/(\w) \1+/g;
var index=0;
var value= ';

Str.replace (Re,function ($0,$1) {
if (index<$0.length) {
Index=$0.length;
value=$1;
}
})

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Match Chinese: [\u4e00-\u9fa5]
Line trailing space: ^\s*|\s*$
Email:^\[email protected][a-z0-9]+ (\.[ a-z]+) {1,3}$
URL: [a-za-z]+://[^\s]*
QQ No.: ^[1-9][0-9]{4,9}$
Postcode: [1-9]\d{5}
ID: [1-9]\d{14}| [1-9]\d{17}| [1-9]\d{16}x

Summary of JS Regular expressions