Send an input value via ajax

Question

Hello folks I have an input with the following function

<input id="cpf"onblur="buscacpf()">

below is the function .

<script>
function buscacpf() {
  var x = document.getElementById("cpf").value;

alert(x);
}
</script> 

something very basic namely when I left this input by the onblur method it returns me the value that was typed in the input, however I need to take this value that is a Cpf and return the name of the client, some searches done on the internet led me to do this via ajax, but I’m a beginner and I don’t know how to make it work.

As it is the ajax script that will take this value and send to another page, this working would already be 50% because the query I know how to do there would only be to return this query to the first page .