A detailed explanation of the Replace method in JavaScript _javascript tips

Definitions and usage

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

Stringobject.replace (regexp/substr,replacement)

Parameters	Description
Regexp/substr	Necessary. The RegExp object that prescribes the substring or pattern to be replaced. Note that if the value is a string, it is used as the direct text pattern to retrieve, not first converted to the RegExp object.
Replacement	Necessary. A string value. Provides a function that replaces text or generates alternate text.

return value

A new string that is replaced with replacement for the first match of RegExp or after all matches have been made.

Regular characters

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

Character	Replace text
$$	Direct measure sign (just as ' $$ ' character used)
$&	A string that matches a regular match
$`	Matches the character to the left of the string
$'	Match the character to the right of the string
$1,$2,$,3,..., $n	Corresponding packet matching results in matching results

The following examples for you to introduce:

Example 1

In this case, we'll use "w3school" to replace "Microsoft" in the string:

<script type= "Text/javascript" >
var str= "Visit microsoft!"
document.write (Str.replace (/microsoft/, "W3school")
</script>

Output:

Visit w3school!

Example 2

In this case, we will perform a global substitution, which is replaced with "W3school" whenever "Microsoft" is found:

<script type= "Text/javascript" >
var str= "Welcome to microsoft! "
Str=str +" We are proud to announce this is Microsoft has "
Str=str +" one of the largest WEB developers sites in t He world. "
document.write (Str.replace (/microsoft/g, "W3school")
</script>

Output:

Welcome to w3school! We are proud to announce that W3school
has one of the largest WEB developers sites in the world.

Example 3

You can use the code provided in this example to ensure that matching string uppercase characters are correct:

Text = "JavaScript Tutorial";
Text.replace (/javascript/i, "JavaScript");

Example 4

In this case, we'll convert "Doe, John," to "John Doe" in the form of:

Name = "Doe, John";
Name.replace (/(\w+) \s*, \s* (\w+)/, "$ $");

Example 5

In this case, we'll replace all the curly quotes with straight quotes:

Name = ' "A", "B";
Name.replace ([^ "]*)"/g, "' $ '");

Example 6

In this case, we will convert the first letter of all words in the string to uppercase:

Name = ' AAA bbb CCC ';
Uw=name.replace (/\b\w+\b/g, function (word) {return
 word.substring (0,1). toUpperCase () +word.substring (1);}
 );

Regular replacement string

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

Using regular expressions and changing the regular global property to True allows all loser to become hero

Use $& characters to add braces 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}
replaces the content ' ABC ' with $ ' and $ ' characters
. Replace (/b/, "$");
AAC
' abc '. Replace (/b/, "$ '");
ACC
uses group matching to combine the new string
' nimojs@126.com '. 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 arguments (n is the number of matches to the regular)

See examples to help understand:

function logarguments () {  
  console.log (arguments);
["Nimojs@126.com", "Nimojs", "@", "126.com", 0, "nimojs@126.com"] 
  return ' Returns the value will replace the match to the target '
}
Console.log (
  ' nimojs@126.com '. Replace (/(. +) (@) (. *)/,logarguments)
)

Parameters are

Matching to the string (this example is nimojs@126.com, recommended to modify the code above the regular to see matching characters to help understand)
If you are using a group match for more than one, there is no such argument. (The argument for this example is "Nimojs", "@", "126.com".) Recommended modifications regular for/nimo/view the arguments value returned in the console)
Match the corresponding index position of the string (this example is 0)
Raw string (This example is nimojs@126.com)
Use a custom function to change the a-g string to lowercase

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

Use custom functions to make callback substitutions to remove single quotes from inline styles

<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 James Black;" >demo</span>

The above content is small to introduce the avascript in the Replace method, I hope you like.