isFocused
Return true or false if the selected DOM-element currently has focus. If the selector matches multiple elements, it will return true if one of the elements has focus.
Usage
$(selector).isFocused()
Examples
<input name="login" autofocus="" />
it('should detect the focus of an element', () => {
    browser.url('/');
    const loginInput = $('[name="login"]');
    console.log(loginInput.isFocused()); // outputs: false
    loginInput.click();
    console.log(loginInput.isFocused()); // outputs: true
})