Global / Window

`btoa`

Creates a Base64-encoded ASCII string from a binary string

Syntax

JavaScript

btoa(stringToEncode)

Parameters

Parameter	Type	Description
stringToEncode	string	The binary string to encode

Return Value

An ASCII string containing the Base64 representation

Examples

Basic Usage

const encoded = btoa('Hello World');
console.log(encoded); // 'SGVsbG8gV29ybGQ='

Practical Example

const data = JSON.stringify({ name: 'Alice', age: 30 });
const base64 = btoa(data);
console.log(base64); // 'eyJuYW1lIjoiQWxpY2UiLCJhZ2UiOjMwfQ=='

Advanced Usage

function createBasicAuth(user: string, pass: string) {
  return 'Basic ' + btoa(`${user}:${pass}`);
}
console.log(createBasicAuth('admin', 'secret'));

Understanding btoa

The btoa method in JavaScript creates a Base64-encoded ASCII string from a binary string. It belongs to the window object and is one of the most widely used methods for working with window values in modern JavaScript and TypeScript applications.

The method signature is btoa(stringToEncode). It accepts 1 parameter: stringToEncode. When called, it returns an ascii string containing the base64 representation. Understanding when and how to use btoa() helps you write more expressive, readable code.

Common use cases for btoa include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like window-atob, enabling you to chain operations together for complex data manipulation pipelines.

Browser support for btoa is excellent across all modern browsers including Chrome, Firefox, Safari, and Edge. It is also fully supported in Node.js and Deno. For older environments, transpilation with Babel or a polyfill may be needed.