The Replace method in JavaScript

Definition and usage

The replace () method is used to replace other characters with some characters in a string, or to replace a substring that matches a regular expression.

Stringobject.replace (regexp/substr,replacement)

Parameters	Description
Regexp/substr	Necessary. A RegExp object that specifies the substring or pattern to replace. Note that if the value is a string, it is used as the direct volume text pattern to be retrieved, instead of being converted to the RegExp object first.
Replacement	Necessary. A string value. A function that specifies replacement text or generates alternate text.

return value

A new string that is obtained after the first match or all matches of regexp have been replaced with replacement .

Regular characters

Replacevalue can be a string. If there are several specific characters in the string, it is converted to a specific string.

Character	Replace text
$$	Direct volume symbol (just as ' $$ ' word trailing characters)
$&	A string that matches a regular match
$`	Match the character to the left of the string
$	Match the character to the right of the string
$1,$2,$,3,..., $n	Matching results for the corresponding grouped matches

Regular Replacement string

' I am loser,you is loser '. Replace (/loser/g, ' hero ')//I am hero,you are hero

Use regular expressions and change the regular global property to True to make all loser become hero

Use $& characters to add parentheses to matching characters

var sstr= ' discusses the use of Replace in regular expressions '; Sstr.replace (/Regular expression/, ' {$&} '); // discuss the use of Replace in {regular expression}

Replace content with $ ' and $ ' characters

' ABC '. Replace (/b/, "$ '"); // AAC' abc '. Replace (/b/, "$ '"); // ACC

Combine new strings with grouping matches

' [email protected] '. Replace (/(. +) (@) (. *)/, "$2$1")//@nimojs

The Replacevalue parameter can be a function

The replacevalue in Stringobject.replace (Searchvalue,replacevalue) can be a function.
If Replacevalue is a function, then the arguments of this function will have n+3 parameters (the number of times that n matches the regular match)

First look at examples to help understand:

function logarguments () {        console.log (arguments); //  return     ' returns ' value will replace the match to the target '}console.log    (' [email protected] '. Replace (/(. +) (@) (. * )/, logarguments))

Parameters are

1. Match to the string (this example is [email protected], it is recommended to modify the above code of the regular to see the matching characters to help understand)
2. If the regular uses a grouping match for more than one otherwise there is no this parameter. (The parameters for this example are "Nimojs", "@", "126.com", respectively.) Recommended modification Regular is/nimo/view the arguments value returned in console)
3. Match the corresponding index position of the string (this example is 0)
4. Raw string (This example is [email protected])

Use a custom function to change the a-g string to lowercase

' JAVASCRIPT '. Replace (/[a-g]/g,function() {    return arguments[0].tolowercase ();}) // JaVaScRIPT

Use a custom function to make a callback replace the single quotation mark in the inline style

' <span style= ' font-family:\ ' Microsoft Ya Black '; >demo</span> '. Replace (/\ ' [^ ']+\ '/g,function() {          var sresult=arguments[0 ];    Console.log (sresult); // ' Microsoft Ya Black '    Sresult=sresult.replace (/\ '/g, ');    Console.log (sresult); // Microsoft Ya-Black    return Sresult;}) // <span style= "font-family: Microsoft Jacob Black;" >demo</span>

The Replace method in JavaScript