Them login forms

Forms.js

var setField = function(fieldName, setValue) { 
    document.getElementsByName(fieldName).item(0).value = setValue; 
}; 
setField('web_auth_user[username]', 'xxx'); 
setField('web_auth_user[password]', 'xxx'); 
var inputs = document.getElementsByTagName('input'); 
var submitButton = inputs.item(inputs.length - 1); 
submitButton.click()