Javascript File Handling.js

// Text File

fetch('file.txt')
  .then(response => response.text())
  .then(text => console.log(text))


// ----------------------------------------------------------------------------

// JSON File

fetch('file.json')
  .then(response => response.json())
  .then(jsonResponse => console.log(jsonResponse))


// ----------------------------------------------------------------------------

// XML File

fetch('file.xml')
  .then(response => response.text())
  .then(str => (new window.DOMParser()).parseFromString(str, "text/xml"))
  .then(data => console.log(data))

Pretty Print JSON.js

document.getElementById("json").innerHTML = JSON.stringify(json, undefined, 2);
// JSON.stringify(JSON data, replacer, spacing)