WordPress Rest API

// function.php wp_enqueue_scripts
wp_localize_script( 'main-js', 'rootUrl', array(
  'siteUrl' => get_site_url()
) );


// main.js
var ourRequest = new XMLHttpRequest();
ourRequest.open('GET', rootUrl.siteUrl + '/wp-json/wp/v2/posts');
ourRequest.onload = function() {
  if (ourRequest.status >= 200 && ourRequest.status < 400) {
    var data = JSON.parse(ourRequest.responseText);
    console.log(data);
    // createHtml(data);
  } else {
    console.log("We connected to the server, but it returned an error.");
  }
};

ourRequest.onerror = function() {
  console.log("Connection error");
};

ourRequest.send();

// function createHtml(postData) {}