The JS character replaces replace () function usage detailed explanation

The parameter replacement of the replace () method can be a function rather than a string. In this case, each match calls the function, and the string it returns is used as the replacement text. The first parameter of the function is a string that matches the pattern. The next argument is a string that matches the subexpression in the pattern, and can have 0 or more of these parameters. The next argument is an integer that declares where the match appears in the Stringobject. The last parameter is the stringobject itself

Way one, the simplest common way

The code is as follows	Copy Code
<script language= "JavaScript" > var stringobj= "End ancient People's Republic, end ancient people"; Replace the spelling "end ancient" as "China" and returns the replaced new character The value of the original string stringobj has not changed var newstr=stringobj.replace ("End Ancient", "China"); alert (NEWSTR); </script>

Method two, using the callback function of the fixed parameter

The code is as follows	Copy Code
var rep2=url.replace (reg,function (M,P1,P2,P3) {return p1+ "showbook.aspx?bookid=" +p3+ "&chapterid=" +p3}); alert (REP2);

Method III, using a callback function with a non fixed parameter

The code is as follows	Copy Code
var rep3=url.replace (Reg,function () {var args=arguments; return args[1]+ showbook.aspx?bookid= "+args[2]+" & Chapterid= "+args[3];}"; alert (REP3);

Method Four, regular mode substitution

The code is as follows	Copy Code
Convert Word-word to Wordword function Camelize (s) { Return S.replace (/-(w)/g, function (Strmatch, p1) { return P1.touppercas (); }); } If

There are N of N times a typo, is not also to perform N-second side replace method to replace the typo?? Oh, don't be afraid, there is a regular expression after the use of a typo to perform a replace method. After the program has been improved, the following code

JS Code

The code is as follows	Copy Code
<script language= "JavaScript" > var reg=new RegExp ("End Ancient", "G"); Create a regular RegExp object var stringobj= "End ancient People's Republic, end ancient people"; var newstr=stringobj.replace (Reg, "China"); alert (NEWSTR); </script>

Analysis of problems in the process of use

The code is as follows	Copy Code
Str=str.replace ("Hand", "hand.gif");

Output: Hand.gif hand Hand

Replace only once ... :(

So write

The code is as follows	Copy Code
str = str.replace (/hand/, "Hand.gif")

Invalid...
All replacements should be G,

The code is as follows	Copy Code
str = str.replace (/hand/g, "Hand.gif")

Or not: (

Later Baidu, Google found the result is the original to use () enclosed, will replace () in the Dongdong. The correct wording is as follows:

The code is as follows	Copy Code
str = "Hand hand hand"; Str=str.replace (/(hand)/g, "hand.gif"); document.write (str); Correct output: Hand.gif hand.gif hand.gif.

JS is another way of writing is the use of regexp:

code is as follows	copy code
equivalent to: Reg = new RegExp ("(Hand)", "G");    str = str.replace (reg, ' hand.gif ');