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The _javascript skill of the knowledge summary of Js Regular expression

Source: Internet
Author: User
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Regular expression:

1, what is RegExp? RegExp is the abbreviation for regular expressions. The RegExp object is used to specify what is retrieved in the text.

2, the definition of Regexp:var + variable name =new RegExp ();

3, the RegExp object has 3 methods:

1 Test () retrieves the specified value in the string, and the return value is true or false.

Copy Code code as follows:

var p1=new Reg ("E");
document.write (Reg.test ("Welcome to china!"));

2) EXEC ()

Copy Code code as follows:

var p1=new Reg ("E");
document.write (Reg.exec ("Welcome to china!"));

3) Compile ()

Copy Code code as follows:

var p1=new Reg ("E");
document.write (Reg.compile ("Welcome to china!"));

4, modifier

1) I perform an insensitive match for case sensitivity

2) G perform global match

3) m performs multiple line matching

5, square brackets (used to find a range of characters)

1) [ABC] find any character between square brackets

2) [^ABC] finds any characters that are not between brackets

3) [0-9] Find the number between any 0-9

4) [A-z] find characters between any lowercase a-Z

5) [A-z] find any characters between uppercase A-Z

6) [A-z] find any character between uppercase A and lowercase Z

7) [ADGK] finds any character within a given set

8) [^ADGK] finds any character outside a given set

9) (Red|biue|green) to find any given option

6, meta characters

1) \w: Find word characters

2) \w: Find non-word characters

3) \d: Find numbers

4) \d: Find non-numeric characters

7. Measure words

n+ matches any string that contains at least one n.

n matches any string containing 0 or more n.

N? matches any string that contains 0 or one n.

N{x} matches a string that contains a sequence of X N.

N{x,y} matches a string containing a sequence of X or Y N.

N{x, a string that matches a sequence containing at least X N.

n$ matches any string ending with N.

^n matches any string that starts with N.

? =n matches any string immediately followed by the specified string n.

?! n matches any string that is not followed by the specified string n.

"Exercise 1" to determine whether the input ID card format is correct

Copy Code code as follows:

<body>
<label> Please enter your ID number:</label>
<input name= "" type= "text" id= "Shenfen"/>
<input name= "" type= "Submit" id= "Textfi" value= "Submit 1" onclick= "Test ()"/><!--submit button, triggering function-->
</body>
<!--determine whether the ID card is entered correctly-->
<script>
function test ()
{
var reg=new RegExp (/^[0-9]{17}[0-9| x]$/);<!--The format of the regular expression: begins with/^, ends with $/, and the number and letter ranges are in brackets-->
var Text=document.getelementbyid ("Shenfen") .value;<!--the ID of the string that entered the text box corresponds to the ID of the text box-->
Judge whether the area is legal (with If...else)
if (reg.test (text))
{
Alert ("Input is correct")
}
Else
{
Alert ("Input error");
}
}
</script>

Effect Chart:

"Exercise 2" Determines whether the entered mailbox is in the correct format

Copy Code code as follows:

<body>
<label> Please enter your email:</label>
<input name= "" type= "text" id= "Youxiang"/>
<input name= "" type= "Submit" value= "Submit 2" onclick= "Y ()"/>
</body>
<script>
function y ()
{
var yx=new RegExp (/^[0-9| a-z|_]{1,17}@[a-z|0-9]{1,5}. (COM|CN|NET|ORG|CC) $/);
var Shuru=document.getelementbyid ("Youxiang"). Value; <!--defines a variable, calls the entire function, and must write the variable within the function-->
if (Yx.test (Shuru)) <!--test Regular expression Method-->
{
Alert ("Zhengque");
}
Else
{
Alert ("Cuowu");
}
}
</script>

Effect Chart:


Relatively speaking, JS is a very important point of expression, many places need to cooperate with the only line, so the small partners must learn this piece of content.

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