How to encode and decode URL with Javascript

When you request a third-party API, you may pass parameters that contain special characters. This may cause errors for your request. To avoid this situation, you need to encode the URL before sending the request.

Encode URL

Javascript has 2 functions that help you encode a URL:

encodeURI(): encode a full URL. It doesn't encode ~!@#$&*()=:/,;?+'
encodeURIComponent(): encode a part of the URL. It doesn't encode -_.!~*'()

Examples

Encode URL

const URL = "https://phongduong.dev/blog/kiểm tra tiếng Việt"

console.log(encodeURI(URL)) // https://phongduong.dev/blog/ki%E1%BB%83m%20tra%20ti%E1%BA%BFng%20Vi%E1%BB%87t
console.log(encodeURIComponent(URL)) // https%3A%2F%2Fphongduong.dev%2Fblog%2Fki%E1%BB%83m%20tra%20ti%E1%BA%BFng%20Vi%E1%BB%87t

Encode parameters

const URL = "https://phongduong.dev"
const URLParam = "https://example.com"
const queryParam = "Đây là tiếng Việt"

console.log(`${URL}?url=${encodeURIComponent(URLParam)}`) // https://phongduong.dev?url=https%3A%2F%2Fexample.com
console.log(`${URL}?q=${encodeURIComponent(queryParam)}`) // https://phongduong.dev?q=%C4%90%C3%A2y%20l%C3%A0%20ti%E1%BA%BFng%20Vi%E1%BB%87t

Decode URL

Javascript provides decodeURI() and decodeURIComponent()to decode a URL. You can use them to decode the corresponding encoding function's result

console.log(decodeURI("https://phongduong.dev/blog/ki%E1%BB%83m%20tra%20ti%E1%BA%BFng%20Vi%E1%BB%87t")) // https://phongduong.dev/blog/kiểm tra tiếng Việt
console.log(decodeURIComponent("https%3A%2F%2Fphongduong.dev%2Fblog%2Fki%E1%BB%83m%20tra%20ti%E1%BA%BFng%20Vi%E1%BB%87t")) // https://phongduong.dev/blog/kiểm tra tiếng Việt