Android JavaScript autocomplete form WebView

Question

With this code, I can easily paste username and password automatically on facebook.com
The purpose is to automatically paste username and password for each site chosen by the user. Many apps do it, but I have not found the way. Thanks for your help

@Override
public void onPageFinished(WebView view, String url) {
    super.onPageFinished(view, url);
    progressBar.setVisibility(View.GONE);
    String user = "user";
    String pwd = "pass";
    view.loadUrl("javascript:(function(){document.getElementsByName('email')[0].value='"
            + user
            + "';document.getElementsByName('pass')[0].value='"
            + pwd + "';document.getElementsByTagName('form')[0];})()");
}

Answer 1

Like Speditz said not every login page uses the same name / id element.

In general, most of the websites either use type="email" or type="text" for username, type="password" for password to login, and you can do some field existence checking and perform injection after webpage loaded

view.loadUrl(
    "javascript:window.onload= (function(){"
    + "var selectElementName = document.querySelector('input[type=\"email\"]');"
    +"if(selectElementName){selectElementName.value =  \"" + user + "\";}"
    +"var selectElementName = document.querySelector('input[type=\"text\"]');"
    +"if(selectElementName){selectElementName.value =  \"" + user + "\";}"
    +"var selectElementpassword = document.querySelector('input[type=\"password\"]');"
    +"if(selectElementpassword){selectElementpassword.value =  \"" + pwd + "\";}"
    +"})();"
);

And this is above JavaScript in plain text for easier to understand:

window.onload= function(){

            var selectElementName = document.querySelector('input[type="email"]');
            if(selectElementName){selectElementName.value =  "username";}

            var selectElementName = document.querySelector('input[type="text"]');
            if(selectElementName){selectElementName.value =  "username";}

            var selectElementpassword = document.querySelector('input[type="password"]');
            if(selectElementpassword){selectElementpassword.value =  "password";}
 };