JavaScript String replace() Method

Definition and Usage

replace() The method searches for a value or a regular expression in the string.

replace() The method returns a new string with the replaced value.

replace() The method does not change the original string.

Tip:If you replace the value, only the first instance will be replaced. To replace all instances, use the one with g Regular expressions for modifier sets.

See also:

Regular Expression Tutorial

Regular Expression Reference Manual

Instance

Example 1

Replace Microsoft:

let text = "Visit Microsoft!";
let result = text.replace("Microsoft", "W3School");

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Example 2

Global replacement:

let text = "Mr Blue has a blue house and a blue car";
let result = text.replace(/blue/g, "red");

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Example 3

Global, case-insensitive replacement:

let text = "Mr Blue has a blue house and a blue car";
let result = text.replace(/blue/gi, "red");

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Example 4

Return the function of the replacement text:

let text = "Mr Blue has a blue house and a blue car";
let result = text.replace(/blue|house|car/gi, function (x) {
  return x.toUpperCase();
});

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Syntax

string.replace(regexp, replacement)

Parameters

Parameters Description
regexp

Required. The value to be searched or the regular expression.

This parameter specifies the RegExp object to be replaced.

If this parameter is a string, it will be used as the direct quantity text pattern to be retrieved.
replacement

Required. String.

Specify the replacement text or the function that generates the replacement text.

return value

Type Description
indicates the new string with the specified value replaced.

Technical details

return value

returns a new string, which is replacement replaced regexp the first match or all matches after

of

indicates string string replace() in string method performs a search and replace operation. It will regexp search for replacement matches the substring, then regexp to replace these substrings. If replace() the global flag g is set, then

replacement the method will replace all the matched substrings. Otherwise, it only replaces the first matched substring. If replacement can be a string or a function. If it is a string, then each match will be replaced by the string. However $ characters have specific meanings. As shown in the table below, it explains that the string obtained from the pattern matching will be used for replacement.

character Replacement text
$1, $2, ..., $99 with regexp matches the text from the 1st to the 99th subexpression in
$& with regexp The matched substring.
$` The text to the left of the matched substring.
$' The text to the right of the matched substring.
$$ Direct quantity symbols.

Note:ECMAScript v3 specifies thatreplace() method's parameters replacement can be a function instead of a string. In this case, the function is called for each match, and the string it returns is used as the replacement text. The first parameter of the function is the string of the matching pattern. The following parameters are the strings that match the subexpressions in the pattern, and there can be 0 or more such parameters. The next parameter is an integer that declares the position of the match in string at the position in the string. The last parameter is string itself.

Browser support

replace() It is an ECMAScript1 (ES1) feature.

All browsers fully support ES1 (JavaScript 1997):

Chrome IE Edge Firefox Safari Opera
Chrome IE Edge Firefox Safari Opera
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Relaterade sidor

JavaScript sträng

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