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Definition and usage

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

Grammar

StringObject.replace (regexp,replacement)

Parameter description

Regexp is required. A RegExp object that specifies the schema to replace. Note that if the value is a string, it is treated as an immediate amount of text pattern to retrieve, rather than being first converted to a RegExp object.

Replacement is required. A string value. Specifies the function that replaces the text or generates the alternate text.

Return value

A new string is obtained after replacing the first match or all matches of regexp with replacement.

Description

The replace () method of the string stringObject performs the find and replace operation. It looks for substrings that match regexp in stringObject and replaces them with replacement. If regexp has the global flag g, then the replace () method replaces all matching substrings. Otherwise, it replaces only the first matching substring.

Replacement can be either a string or a function. If it is a string, then no matches will be replaced by the string. But the $character in replacement has a specific meaning. As shown in the following table, it indicates that the string obtained from the pattern match will be used for replacement.

Character replacement text

Text of $1, $2,..., and $99 that matches subexpressions 1 through 99 in regexp.

$& the substring that matches regexp.

The text to the left of the matching substring.

$'the text to the right of the matching substring.

% direct measurement symbol.

Note: ECMAScript v3 states that the parameter replacement of the replace () method can be a function rather than a string. In this case, the function is called for each match, and the string it returns is used as replacement text. The first argument to this function is the string that matches the pattern. The next parameter is a string that matches the subexpression in the pattern, and there can be 0 or more such parameters. The next parameter is an integer that declares where the match occurs in the stringObject. The last parameter is stringObject itself.

Example

Example 1

In this example, we will replace "Microsoft" in the string with "W3School":

The copy code is as follows:

Var str= "Visit Microsoft!"

[xss_clean] (str.replace (/ Microsoft/, "W3School"))

Output:

Visit W3School!

Example 2

In this case, we will perform a global replacement, and whenever "Microsoft" is found, it will be replaced with "W3School":

The copy code is as follows:

Var str= "Welcome to Microsoft!"

Str=str + "We are proud to announce that Microsoft has"

Str=str + "one of the largest Web Developers sites in the world."

[xss_clean] (str.replace (/ Microsoft/g, "W3School")

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 the matching string uppercase characters are correct:

The copy code is as follows:

Text = "javascript Tutorial"

Text.replace (/ javascript/i, "JavaScript")

Example 4

In this example, we will convert "Doe, John" to the form of "John Doe":

The copy code is as follows:

Name = "Doe, John"

Name.replace (/ (\ w +)\ swords,\ s * (\ w +) /, "$2 $1")

Example 5

In this example, we will replace all flower quotation marks with straight quotation marks:

The copy code is as follows:

Name = "a", "b"'

Name.replace (/ "([^"] *) "/ g,"'$1' ")

Example 6

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

The copy code is as follows:

Name = 'aaa bbb ccc'

Uw=name.replace (/\ b\ w +\ bzag g, function (word) {

Return word.substring (0Pol 1). ToUpperCase () + word.substring (1);}

);

Example 7

The copy code is as follows:

Var str= "fsaf$a$assdfdasfa$a$dsfadsf"

Var strr='\ $'+ 'astatine'\ $'

Var name = "a", "b"'

Var reger=new RegExp ("[\ $] a [\ $]", "gm")

Alert (str.replace (reger,'555888'))

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