Google Invisible Recaptcha - Enter press key not work - recaptcha

Question

I implemented google invisible recaptcha on my login form but when i submit the form by pressing Enter key, it does not send any response token. However, when i clicked button whose type submit, it validates successfully.
How can I get response with both press enter and click button?
C# - MVC application used as technologhy. #Model.GoogleRecaptchaSiteKey property is filled on my application.
Here is my login form html
#using (Html.BeginForm("Login", "Account", new { ReturnUrl = Request.QueryString["ReturnUrl"] }, FormMethod.Post, new { #class = "login-form", id = "login-form" }))
{
<div class="login-form">
<h3 class="form-title">Login Form</h3>
<div class="form-group">
<!--ie8, ie9 does not support html5 placeholder, so we just show field title for that-->
<label class="control-label visible-ie8 visible-ie9">Kullanıcı Adı</label>
<div class="input-group">
<div class="input-group-addon">
<i class="fa fa-user"></i>
</div>
#Html.TextBoxFor(f => f.UserName, new { title = "Kullanıcı adınızı giriniz.", #class = "form-control placeholder-no-fix", #placeholder = "Kullanıcı Adı", #value = "", #autofocus = "true" })
</div>
#Html.ValidationMessageFor(m => m.UserName)
</div>
<div class="form-group">
<label class="control-label visible-ie8 visible-ie9">password</label>
<div class="input-group" id="show_hide_password">
<div class="input-group-addon">
<i class="fa fa-lock"></i>
</div>
#Html.TextBoxFor(f => f.Password, new { #title = "password.", #type = "password", #class = "form-control placeholder-no-fix", #placeholder = "password", #value = "" })
<div class="input-group-addon">
<i class="fa fa-eye-slash" id="i_show_hide_password" aria-hidden="true"></i>
</div>
</div>
#Html.ValidationMessageFor(m => m.Password)
</div>
<div class="form-actions">
#Html.AntiForgeryToken()
<input id="login" type="submit" class="btn green pull-right g-recaptcha" data-size="invisible" data-sitekey="#Model.GoogleRecaptchaSiteKey" data-callback="onSubmit" value="Login" />
#Html.ValidationMessage("reCaptcha")
<br />
</div>
</div>
}
Script is below here
function onSubmit(token) {
document.getElementById("login-form").submit();
}