How do you encode a URL in JavaScript?

Depending on what you need to do, there are 2 JavaScript functions what will help you.

The first is encodeURI(), and the second is encodeURIComponent().

Note: you might read about escape(), but that is deprecated and should not be used.

Those 2 methods differ in which characters they do encode.

In details, encodeURI() does not encode ~!@#$&*()=:/,;?+ and encodeURIComponent() does not encode -_.!~*'(), encoding all the other characters. Why do they differ? Because they are meant for different uses:

  • encodeURI() is meant to encode a full URL
  • encodeURIComponent() is meant to encode a single URL parameter value

If you were to call encodeURIComponent() on a full URL, since it does encode /, the URL path separators would be encoded as well (among other things):

encodeURI("http://flaviocopes.com/ hey!/")
//"http://flaviocopes.com/%20hey!/"
encodeURIComponent("http://www.example.org/a file with spaces.html")
// "http%3A%2F%2Fflaviocopes.com%2F%20hey!%2F"

MDN proposes an improvement to adhere to the RFC 3986 standard (http://tools.ietf.org/html/rfc3986), by implementing the following function:

const fixedEncodeURIComponent = (str) => {
  return encodeURIComponent(str).replace(/[!'()*]/g, (c) => {
    return '%' + c.charCodeAt(0).toString(16)
  })
}

You call it for every single parameter that you’ll add to the URL.

The encodeURI() and encodeURIComponent() methods have a corresponding decodeURI() and decodeURIComponent() which does the opposite job which you can use on the backend if you use Node.js.