What is the string replace() method in JavaScript?

The replace() method in JavaScript is used to replace a substring or regular expression of a string with another substring or regular expression.

Syntax

The replace() method can be declared as shown in the code snippet below:

string.replace(oldValue, newValue)

Parameters

  • oldValue: The substring or regular expression of the string that will be replaced with newValue.

  • newValue: The substring or regular expression that will replace oldValue in the string.

Return value

The replace() method returns the string after oldValue is replaced with newValue.

The string itself is not changed. The changes are made in a copy of the string, and that copy is returned.

Browser compatibility

The following browsers support the replace() method:

  • Chrome 1
  • Edge 12
  • Firefox 1
  • Internet Explorer 5.5
  • Opera 4
  • Safari 1

Code

Consider the code snippet below, which demonstrates the use of the replace() method:

let str = "Hello World! This is replace() eg. code";
console.log("str before replace(): " + str);
let str2 = str.replace("eg.", "example");
console.log("str after replace(): " + str2);

Explanation

  • We declare a string str in line 1.

  • We use the replace() method in line 4 to replace the substring "eg." with the substring "example" in str.

  • The changes are made and returned in the string str2, and str remains unchanged.

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