The replace() method in JavaScript is used to find and replace specified characters or substrings in a string. The usage is: string.replace(replaceWhat, replaceWith[, count]). It can perform operations such as string replacement, regular expression replacement, partial replacement, find and replace functions, and global replacement.
Usage of replace() in JavaScript
What is replace()?
replace() method is used to find and replace specified characters or substrings in a string.
Usage
string.replace(replaceWhat, replaceWith[, count]);
Parameters
- replaceWhat: Character or subtitle to find string.
- replaceWith: The character or substring to be replaced.
- count (optional): The number of times to replace (default is all).
Return value
Returns the replaced string without modifying the original string.
Detailed usage
1. String replacement
Replace the specified character with another character:
let str = "Hello World"; str.replace("World", "Universe"); // "Hello Universe"
2. Regular expression replacement
Find and replace substrings using regular expressions:
let str = "This is a test sentence."; str.replace(/\s/g, "-"); // "This-is-a-test-sentence."
3. Partial replacement
Limit the number of times to be replaced:
let str = "The quick brown fox jumps over the lazy dog."; str.replace("the", "a", 1); // "The quick brown fox jumps over a lazy dog."
4. Find and replace function
Use the callback function to specify the replacement content:
let str = "John Doe"; str.replace(/(?<name>\w+) (?<surname>\w+)/, match => `${match.groups.surname}, ${match.groups.name}`); // "Doe, John"
5. Global replacement
g
flag globally matches and replaces all matching substrings:
let str = "The lazy dog jumped over the lazy fox."; str.replace(/lazy/g, "quick"); // "The quick dog jumped over the quick fox."
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