devtools.detect.js

/***
  ** 
Ref: https://github.com/sindresorhus/devtools-detect
***/
var devtools = {
  isOpen: false,
  orientation: undefined,
},
threshold = 160;

// for older browser version check for globalThis object
if (typeof globalThis === 'undefined') {
  var globalThis = window;
}

var emitEvent = function emitEvent(isOpen, orientation) {
  globalThis.dispatchEvent(new globalThis.CustomEvent('devtoolschange', {
    detail: {
      isOpen: isOpen,
      orientation: orientation
    }
  }));
};

var detectDevtoolsFn = function detectDevtoolsFn() {
  var _ref = arguments.length <= 0 || arguments[0] === undefined ? {} : arguments[0],
    _refEmitEvents = _ref.emitEvents,
    emitEvents = _refEmitEvents === undefined ? true : _refEmitEvents;

  var widthThreshold = globalThis.outerWidth - globalThis.innerWidth > threshold,
    heightThreshold = globalThis.outerHeight - globalThis.innerHeight > threshold,
    orientation = widthThreshold ? 'vertical' : 'horizontal';

  if (!(heightThreshold && widthThreshold) && (globalThis.Firebug && globalThis.Firebug.chrome && globalThis.Firebug.chrome.isInitialized || widthThreshold || heightThreshold)) {
    if ((!devtools.isOpen || devtools.orientation !== orientation) && emitEvents) {
      emitEvent(true, orientation);
    }

    devtools.isOpen = true;
    devtools.orientation = orientation;
  } else {
    if (devtools.isOpen && emitEvents) {
      emitEvent(false, undefined);
    }

    devtools.isOpen = false;
    devtools.orientation = undefined;
  }
};

window.addEventListener("load", function() {
  // call devtools fn to check if it is open or not
  detectDevtoolsFn({ emitEvents: false }); 
  if (devtools.isOpen) {
    console.log('DevTools is open on Browser Window!');
  } else {
    console.log('DevTools is closed on Browser Window!');
  }
});