JS uses the replace () method and regular expression to search and replace strings.

1. Replacement of JS strings and use of the replace () method

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:

Example 1:
Copy codeThe Code is as follows:
Var str = "Hello world! ";
Document. write (str. replace (/world/, "phper "));
Example 2:
Copy codeThe Code is as follows:
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:
Copy codeThe Code is as follows:
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:
Copy codeThe Code is as follows:
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:
Copy codeThe Code is as follows:
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:
Copy codeThe Code is as follows:
Var reg = new RegExp ("(\ w +), (\ d +), (\ w +)", "gmi ");
Var m = reg. test ("Lili, 14, China ");
Alert (RegExp. $1 );
Alert (RegExp. $2 );
Alert (RegExp. $3 );