JavaScript String replaceAll()

 const message = "ball bat"; 
// replace all occurrence of b with c let result = message.replaceAll('b', 'c');
 console.log(result); // Output: call cat

replaceAll() Syntax

The syntax of replaceAll() is:

 str.replaceAll(pattern, replacement)

Here, str is a string.

replaceAll() Parameter

The replaceAll() method takes in:

• pattern - either a substring or a regex that is to be replaced
• replacement - the pattern is replaced with this replacement (can be either a string or a function)

replaceAll() Return Value

• The replaceAll() method returns a new string, with all matches of a pattern replaced by a replacement.

Note: A RegExp without the global ("g") flag will throw a TypeError.

Example 1: Using replaceAll()

 const text = "Java is awesome. Java is fun."; // passing a string as the first parameter 
let pattern = "Java"; let new_text = text.replaceAll(pattern, "JavaScript");
 console.log(new_text); // passing a regex as the first parameter 
pattern = /Java/g; new_text = text.replaceAll(pattern, "JavaScript");
 console.log(new_text);

Output

 JavaScript is awesome. JavaScript is fun JavaScript is awesome. JavaScript is fun.

Replace Without Considering Uppercase/Lowercase

The replaceAll() method is case sensitive. To perform the case-insensitive replacement, you need to use a regex with a i switch (case-insensitive search).

Example 2: Case-Insensitive Replacement

 const text = "javaSCRIPT JavaScript"; // all occurrences of javascript is replaced 
let pattern = /javascript/gi; // case-insensitive and global search let new_text = text.replaceAll(pattern, "JS");
 console.log(new_text); // JS JS

Output

 JS JS

Example 3: Passing Function as a Replacement

You can also pass a function (instead of a string) as the second parameter to the replaceAll() method.

 const text = "3.1415"; // generate a random digit between 0 and 9 function generateRandomDigit() { return Math.floor(Math.random() * 10); } // regex to match a digit 
const pattern = /\d/g; const new_text = text.replaceAll(pattern, generateRandomDigit);
 console.log(new_text);

Output

 4.3518

You may get different output when you run this program. It's because the first digit in text is replaced with a random digit between 0 and 9.

Also Read:

• JavaScript String replace()