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Search for and replace Javascript strings

Source: Internet
Author: User
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In js, We need to search for strings and use indexOf and then replace (). In fact, we don't need to do this at all. We just need a simple positive table expression under replace.

The replace (regexp, replacement) method has two parameters. The first parameter can be a plain text string or a RegExp object. For details, see the use of the RegExp object; the second parameter can be a string or a function.

The following is an example of JS string replacement:

If it is a normal replacement, you can only Replace the first one. To replace all, you must use a regular expression. The following code shows the differences between the two:

The Code is as follows: Copy code


<Html>
<Head>
<Title> test </title>
<Script language = "JavaScript">
<! --
Var s = "testtest ";
 
// G in the second parameter indicates that all matches, And I indicates that case-insensitive
Var regS = new RegExp ("test", "gi ");
 
Alert (s. replace ("test", "Hello"); // replace only one
Alert (s. replace (regS, "Hello"); // replace all
// -->
</Script>
</Head>
<Body>
</Body>
</Html>

Next let's look at the instance

Example 1:

The Code is as follows: Copy code

Var str = "Hello world! ";
Document. write (str. replace (/world/, "phper "));

Example 2:

The Code is as follows: Copy code

Var reg = new RegExp ("(\ w +), (\ d +), (\ w +)", "gmi ");
Var info = "Lili, 14, China ";
Var rep = info. replace (reg, "She is $1, $2 years old, come from $3 ");
Alert (rep );

Example 3:

The Code is as follows: Copy code
Var reg = new RegExp ("(\ w +), (\ d +), (\ w +)", "gmi ");
Var info = "Lili, 14, China ";
Var name, age, from;
Function prase_info (m, p1, p2, p3) {// you can also use a non-explicit parameter, obtained using arguments
Name = p1;
Age = p2;
From = p3;
Return "She is" + p1 + "," + p2 + "years old, come from" + p3;
}
Var rep = info. replace (reg, prase_info );
Alert (rep );
Aler (name );

2. Use of RegExp objects

JavaScript provides a RegExp object to perform operations and functions on regular expressions. Each regular expression pattern corresponds to a RegExp instance. You can create an instance of the RegExp object in two ways.

Use RegExp's explicit constructor Syntax: new RegExp ("pattern" [, "flags"]); Use RegExp's implicit constructor in plain text format: /pattern/[flags]. In Example 4, the two statements are equivalent.

Example 4:

The Code is as follows: Copy code

Var re1 = new RegExp ("\ d {5 }");
Var re2 =/d {5 }/;

3. string search and use of the exec () method

The exec () method returns an array containing matching results. If no match is found, the return value is null.

Example 5:

The Code is as follows: Copy code

Var reg = new RegExp ("(\ w +), (\ d +), (\ w +)", "gmi ");
Var m1_reg.exe c ("Lili, 14, China ");
Var s = "";
For (I = 0; I <m. length; I ++ ){
S = s + m [I] + "n ";
}
Alert (s );

4. Use of the test () method

RegExpObject. test (string)

If the string contains the text that matches RegExpObject, true is returned; otherwise, false is returned.

Example 6:

The Code is as follows: Copy code

Var reg = new RegExp ("(\ w +), (\ d +), (\ w +)", "gmi ");
Var m = reg. test ("Lili, 14, China ");
Alert (RegExp. $1 );
Alert (RegExp. $2 );
Alert (RegExp. $3 );

Add the js replacement method.


The return value is the string after the replacement operation is executed.

String. replace ()
 

The Code is as follows: Copy code
Var text = "javascript is very powerful! ";
Text. replace (/javascript/I, "JavaScript ");

// Return: JavaScript is very powerful!
String. replace () replace all Target Characters
 

The Code is as follows: Copy code
Var text = "javascript is very powerful! JAVASCRIPT is my favorite language! ";
Text. replace (/javascript/ig, "JavaScript ");
// Return: JavaScript is very powerful! JavaScript is my favorite language!

String. replace ()
 

The Code is as follows: Copy code
Var name = "Doe, John ";
Name. replace (/(w +) s *, s * (w +)/, "$2 $1 ");
// Return value: John Doe

String. replace () is used to replace all characters in double quotation marks with characters in brackets.
 

The Code is as follows: Copy code
Var text = '"JavaScript" is very powerful! ';
Text. replace (/"([^"] *) "/g," [$1] ");
// Return: [JavaScript] is very powerful!

String. replace () uppercase letters
 

The Code is as follows: Copy code
Var text = 'a journey of a thousand miles begins with single step .';
Text. replace (/bw + B/g, function (word ){
Return word. substring (0, 1). toUpperCase () +
Word. substring (1 );
});
 
// Return: A Journey Of A Thousand Miles Begins With Single Step.

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

Related Keywords:
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