Detailed explanation on the use of replace of String object in js

Detailed explanation on the use of replace of String object in js_javascript skills

WBOY

Release： 2016-05-16 18:06:28

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Today when I was reading the source code stringH of Qwrap, there was a

copy code The code is as follows:

 
format: function(s, arg0) { 
var args = arguments; 
return s.replace(/{(d )}/ig, function(a, b) { 
return args[(b | 0) 1] || ''; 
}); 
} 

The way to use it is:
alert(format("{0} love {1}.", 'I','You'))//I love you The implementation of
format mainly uses the replace method of the String object:

replace: Returns the characters after text replacement according to the regular expression Copy of string.

1. Commonly used replacement

Copy code The code is as follows:

 
function ReplaceDemo(){ 
var r, re; // Declare variables. 
var ss = "The man hit the ball with the bat.n"; 
ss = "while the fielder caught the ball with the glove."; 
re = /The/g; // Create Regular expression pattern. 
r = ss.replace(re, "A"); // Replace "The" with "A". 
return(r); // Return the replaced string. 
} 
ReplaceDemo(); //A man hit the ball with the bat. while the fielder caught the ball with the glove. 

2. Subexpression in replacement pattern

Copy code The code is as follows:

 
function ReplaceDemo(){ 
var r, re ; // Declare variables. 
var ss = "The rain in Spain falls mainly in the plain."; 
re = /(S )(s )(S )/g; // Create a regular expression pattern. 
r = ss.replace(re, "$3$2$1"); // Swap each pair of words. 
return(r); // Return the result string. 
} 
document.write(ReplaceDemo()); //rain The Spain in mainly falls the in plain. 

Matching regular items: The rain, in Spain, falls mainly ,in the;Execute ss.replace(re, "$3$2$1") operation to complete the exchange of word positions

$1 matches the first (S)

$2 matches (s )

$3 matches the second (S )

3.replace when the second parameter is function

Copy code The code is as follows:

 
function f2c(s){ 
var test = /(d (.d*)?)Fb/ g; //Initialization mode. 
return(s.replace(test,function($0,$1,$2){return((($1-32)) "C");})); 
} 
f2c("Water boils at 212F 3F .2F 2.2F .2");//Water boils at 180C -29C .-30C -29.8C .2 

$0 matches 212F,3F,.2F,2.2F
$1 matches 212,3,.2,2.2
$2 matches the last .2