错误$ .ajax不是函数吗？

Question

I try to call ajax but get this error:

$.ajax not a function

https://jsfiddle.net/q79pbn7t/4/

By the way, ajax working for the others class. What errors can be happen?

This is my code

<button onclick="sendEmail()">hihi</button>
<script>
  function sendEmail() {
    email = 'email'
    $.ajax({
      type: "POST",
      url: "email",
      data: {
        email: email
      },
      success: function(data) {
        alert(data)
      }
    })
    alert(1)
  }
</script>

Answer 1

You first need to include jQuery in order to have $ and $.ajax.

Fiddle link.