JS uses the replace() method and regular expressions to search and replace strings_javascript skills

1. Replacement of JS strings and use of 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, please see the use of RegExp objects; the second parameter can be a string or a RegExp object. a function.

The following is an example of JS string replacement:

Example 1:

Copy code The code is as follows:

var str="Hello world !";
document.write(str.replace(/world/, "phper"));

Example 2:

Copy code The 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 code The 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 non-explicit parameters and use arguments to obtain
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 object

JavaScript provides a RegExp object to complete operations and functions related to regular expressions. Each regular expression pattern corresponds to a RegExp instance. There are two ways to create instances of RegExp objects.

Use the explicit constructor of RegExp, the syntax is: new RegExp("pattern"[,"flags"]); use the implicit constructor of RegExp, in plain text format: /pattern/[flags]. The two statements in Example 4 are equivalent.

Example 4:

Copy code The code is as follows:

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

3. String search and use of exec() method

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

Example 5:

Copy code The code is as follows:

var reg=new RegExp( "(\w ),(\d ),(\w )","gmi");
var m=reg.exec("Lili,14,China");
var s="";
for (i = 0; i < m.length; i ) {
s = s m[i] "n";
}
alert(s);

4. Use of test() method

RegExpObject.test(string)

Returns true if the string string contains text matching RegExpObject, otherwise returns false.

Example 6:

Copy code The 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);