如何在javascript中获取此值？

var value = document.getElementById("example").value;

document.getElementById("button").addEventListener("click", function() {
  var value = document.getElementById("input").value;
  console.log(value);
});

var value = document.forms["myForm"]["myInput"].value;

var xhr = new XMLHttpRequest();
xhr.open("GET", "example.com/api/data", true);
xhr.onreadystatechange = function() {
  if (xhr.readyState === 4 && xhr.status === 200) {
    var response = JSON.parse(xhr.responseText);
    console.log(response.value);
  }
};
xhr.send();