Question

Is it possible to detect, on the client side, whether the user is using an encrypted page or not?

Put another way — I want to know if the URL of the current page starts with http or https.

Answer 1

Use window.location.protocol to check if it is https:

function isSecure() {    return window.location.protocol == 'https:'; } 

Alternatively you can omit specifying ‘window’ if you don’t have a locally scoped location.

function isSecure() {    return location.protocol == 'https:'; }