Find out whether Chrome console is open

I am using this little script to find out whether Firebug is open:

if (window.console && window.console.firebug) {
    //is open
};

And it works well. Now I was searching for half an hour to find a way to detect whether Google Chrome’s built-in web developer console is open, but I couldn’t find any hint.

This:

if (window.console && window.console.chrome) {
    //is open
};

doesn’t work.

EDIT:

So it seems that it is not possible to detect whether the Chrome console is open. But there is a “hack” that works, with some drawbacks:

  • will not work when console is undocked
  • will not work when console is open on page load

So, I am gonna choose Unsigned´s answer for now, but if some1 comes up with a brilliant idea, he is welcome to still answer and I change the selected answer! Thanks!

53 thoughts on “Find out whether Chrome console is open”

  1. I found a way to tell if the Chrome Console is opened or not.
    It’s still a hack but it’s way more accurate and will work weather the console is undocked or not.

    Basically running this code with the console closed takes about ~100 microseconds and while the console is opened it takes about twice as much ~200 microseconds.

    console.log(1);
    console.clear();
    

    (1 millisecond = 1000 microsecond)

    I’ve written more about it here.

    Demo is here.


    Update:

    @zswang has found the current best solution – check out his answer

    Reply
  2. There is a tricky way to check it for extensions with ‘tabs’ permission:

    chrome.tabs.query({url:'chrome-devtools://*/*'}, function(tabs){
        if (tabs.length > 0){
            //devtools is open
        }
    });
    

    Also you can check if it open for your page:

    chrome.tabs.query({
        url: 'chrome-devtools://*/*',
        title: '*example.com/your/page*'
    }, function(tabs){ ... })
    
    Reply
  3. I created devtools-detect which detects when DevTools is open:

    console.log('is DevTools open?', window.devtools.open);
    

    You can also listen to an event:

    window.addEventListener('devtoolschange', function (e) {
        console.log('is DevTools open?', e.detail.open);
    });
    

    It doesn’t work when DevTools is undocked. However, works with the Chrome/Safari/Firefox DevTools and Firebug.

    Reply
  4. requestAnimationFrame (Late 2019)

    Leaving these previous answers here for historical context. Currently Muhammad Umer’s approach works on Chrome 78, with the added advantage of detecting both close and open events.

    function toString (2019)

    Credit to Overcl9ck‘s comment on this answer. Replacing the regex /./ with an empty function object still works.

    var devtools = function() {};
    devtools.toString = function() {
      if (!this.opened) {
        alert("Opened");
      }
      this.opened = true;
    }
    
    console.log('%c', devtools);
    // devtools.opened will become true if/when the console is opened

    regex toString (2017-2018)

    Since the original asker doesn’t seem to be around anymore and this is still the accepted answer, adding this solution for visibility. Credit goes to Antonin Hildebrand‘s comment on zswang‘s answer. This solution takes advantage of the fact that toString() is not called on logged objects unless the console is open.

    var devtools = /./;
    devtools.toString = function() {
      if (!this.opened) {
        alert("Opened");
      }
      this.opened = true;
    }
    
    console.log('%c', devtools);
    // devtools.opened will become true if/when the console is opened

    console.profiles (2013)

    Update: console.profiles has been removed from Chrome. This solution no longer works.

    Thanks to Paul Irish for pointing out this solution from Discover DevTools, using the profiler:

    function isInspectOpen() {
      console.profile();
      console.profileEnd();
      if (console.clear) {
        console.clear();
      }
      return console.profiles.length > 0;
    }
    function showIfInspectIsOpen() {
      alert(isInspectOpen());
    }
    <button onClick="showIfInspectIsOpen()">Is it open?</button>

    window.innerHeight (2011)

    This other option can detect the docked inspector being opened, after the page loads, but will not be able to detect an undocked inspector, or if the inspector was already open on page load. There is also some potential for false positives.

    window.onresize = function() {
      if ((window.outerHeight - window.innerHeight) > 100) {
        alert('Docked inspector was opened');
      }
    }
    Reply
  5. The Chrome developer tools is really just a part of WebKit’s WebCore library. So this question applies to Safari, Chrome, and any other WebCore consumers.

    If a solution exists, it’ll be based off a difference in the DOM when the WebKit web inspector is open and when it’s closed. Unfortunately, this is a kind of a chicken and egg problem because we can’t use the inspector to observe the DOM when the inspector is closed.

    What you may be able to do is write a bit of JavaScript to dump the entire DOM tree. Then run it once when the inspector is open, and once when the inspector is closed. Any difference in the DOM is probably a side-effect of the web inspector, and we may be able to use it to test if the user is inspecting or not.

    This link is a good start for a DOM dumping script , but you’ll want to dump the entire DOMWindow object, not just document.

    Update:

    Looks like there’s a way to do this now. Check out Chrome Inspector Detector

    Reply
  6. Chrome 65+ (2018)

        r = /./
        r.toString = function () {
            document.title = '1'
        }
        console.log('%c', r);

    demo: https://jsbin.com/cecuzeb/edit?output (Update at 2018-03-16)

    package: https://github.com/zswang/jdetects


    When printing “Element” Chrome developer tools will get its id

        var checkStatus;
        
        var element = document.createElement('any');
        element.__defineGetter__('id', function() {
            checkStatus = 'on';
        });
        
        setInterval(function() {
            checkStatus = 'off';
            console.log(element);
            console.clear();
        }, 1000);

    Another version (from comments)

    var element = new Image();
    Object.defineProperty(element, 'id', {
      get: function () {
        /* TODO */
        alert('囧');
      }
    });
    console.log('%cHello', element);
    

    Print a regular variable:

        var r = /./;
        r.toString = function() {
          document.title = 'on';
        };
        console.log(r);
    Reply
  7. Also you can try this: https://github.com/sindresorhus/devtools-detect

    // check if it's open
    console.log('is DevTools open?', window.devtools.open);
    // check it's orientation, null if not open
    console.log('and DevTools orientation?', window.devtools.orientation);
    
    // get notified when it's opened/closed or orientation changes
    window.addEventListener('devtoolschange', function (e) {
        console.log('is DevTools open?', e.detail.open);
        console.log('and DevTools orientation?', e.detail.orientation);
    });
    
    Reply
  8. Very Reliable hack

    Basically set a getter on property and log it in console. Apparently the thing gets accessed only when console is open.

    https://jsfiddle.net/gcdfs3oo/44/

    var checkStatus;
    var indicator = document.querySelector('#devtool-status');
    
    var element = new Image();
    Object.defineProperty(element, 'id', {
      get: function() {
        checkStatus='on';
        throw new Error("Dev tools checker");
      }
    });
    
    requestAnimationFrame(function check() {
      checkStatus = 'off';
      console.dir(element);
      indicator.className  = checkStatus;
      requestAnimationFrame(check);
    });
    .on{
      color:limegreen;
    }
    
    .off{
      color:red;
    }
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.7.1/css/all.css" integrity="sha256-DVK12s61Wqwmj3XI0zZ9MFFmnNH8puF/eRHTB4ftKwk=" crossorigin="anonymous" />
    
    <p>
      <ul>
        <li>
          dev toolbar open: icon is <span class="on">green</span>
        </li>
        <li>
          dev toolbar closed: icon is <span class="off">red</span>
        </li>
      </ul>
    </p>
    <div id="devtool-status"><i class="fas fa-7x fa-power-off"></i></div>
    <br/>
    <p><b>Now press F12 to see if this works for your browser!</b></p>
    Reply
  9. Muhammad Umer’s approach worked for me, and I’m using React, so I decided to make a hooks solution:

    const useConsoleOpen = () => {
      const [consoleOpen, setConsoleOpen] = useState(true)
    
      useEffect(() => {
        var checkStatus;
    
        var element = new Image();
        Object.defineProperty(element, "id", {
          get: function () {
            checkStatus = true;
            throw new Error("Dev tools checker");
          },
        });
    
        requestAnimationFrame(function check() {
          checkStatus = false;
          console.dir(element); //Don't delete this line!
          setConsoleOpen(checkStatus)
          requestAnimationFrame(check);
        });
      }, []);
    
      return consoleOpen
    }
    

    NOTE: When I was messing with it, it didn’t work for the longest time and I couldn’t figure out why. I had deleted console.dir(element); which is critical to how it works. I delete most non-descriptive console actions since they just take up space and aren’t usually necessary to the function, so that was why it wasn’t working for me.

    To use it:

    import React from 'react'
    
    const App = () => {
      const consoleOpen = useConsoleOpen()
    
      return (
        <div className="App">
          <h1>{"Console is " + (consoleOpen ? "Open" : "Closed")}</h1>
        </div>
      );
    }
    

    I hope this helps anyone using React. If anyone wants to expand on this, I would like to be able stop the infinite loop at some point (since I don’t use this in every component) and to find a way to keep the console clean.

    Reply
  10. If you are developers who are doing stuff during development. Check out this Chrome extension. It helps you detect when Chrome Devtoos is opened or closed.

    https://chrome.google.com/webstore/detail/devtools-status-detector/pmbbjdhohceladenbdjjoejcanjijoaa?authuser=1

    This extension helps Javascript developers detect when Chrome Devtools is open or closed on current page.
    When Chrome Devtools closes/opens, the extension will raise a event named ‘devtoolsStatusChanged’ on window.document element.

    This is example code:

     function addEventListener(el, eventName, handler) {
        if (el.addEventListener) {
            el.addEventListener(eventName, handler);
        } else {
            el.attachEvent('on' + eventName,
                function() {
                    handler.call(el);
                });
        }
    }
    
    
    // Add an event listener.
    addEventListener(document, 'devtoolsStatusChanged', function(e) {
        if (e.detail === 'OPENED') {
            // Your code when Devtools opens
        } else {
            // Your code when Devtools Closed
        }
    });
    
    Reply
  11. If your goal is to jam the developer tools, try this (I found a more complicated version of it at a place where JS code was obfuscated, it’s very annoying):

    setTimeout(function() {while (true) {eval("debugger");}}, 0);
    
    Reply
  12. Some answers here will stop working in Chrome 65. Here’s a timing attack alternative that works pretty reliably in Chrome, and is much harder to mitigate than the toString() method. Unfortunately it’s not that reliable in Firefox.

    addEventListener("load", () => {
    
    var baseline_measurements = [];
    var measurements = 20;
    var warmup_runs = 3;
    
    const status = document.documentElement.appendChild(document.createTextNode("DevTools are closed"));
    const junk = document.documentElement.insertBefore(document.createElement("div"), document.body);
    junk.style.display = "none";
    const junk_filler = new Array(1000).join("junk");
    const fill_junk = () => {
      var i = 10000;
      while (i--) {
        junk.appendChild(document.createTextNode(junk_filler));
      }
    };
    const measure = () => {
        if (measurements) {
        const baseline_start = performance.now();
        fill_junk();
        baseline_measurements.push(performance.now() - baseline_start);
        junk.textContent = "";
        measurements--;
        setTimeout(measure, 0);
      } else {
        baseline_measurements = baseline_measurements.slice(warmup_runs); // exclude unoptimized runs
        const baseline = baseline_measurements.reduce((sum, el) => sum + el, 0) / baseline_measurements.length;
    
        setInterval(() => {
          const start = performance.now();
          fill_junk();
          const time = performance.now() - start;
          // in actual usage you would also check document.hasFocus()
          // as background tabs are throttled and get false positives
          status.data = "DevTools are " + (time > 1.77 * baseline ? "open" : "closed");
          junk.textContent = "";
        }, 1000);
      }
    };
    
    setTimeout(measure, 300);
    
    });
    
    Reply
  13. var div = document.createElement('div');
    Object.defineProperty(div,'id',{get:function(){
        document.title = 'xxxxxx'
    }});
    
    setTimeout(()=>console.log(div),3000)
    
    
    Reply
  14. As for Chrome/77.0.3865.75 a version of 2019 not works. toString invokes immediately without Inspector opening.

    const resultEl = document.getElementById('result')
    const detector = function () {}
    
    detector.toString = function () {
    	resultEl.innerText = 'Triggered'
    }
    
    console.log('%c', detector)
    <div id="result">Not detected</div>
    Reply
  15. Developer Tools usually opened with a keyboard shortcut by a professional developer. You can detect these key combinations and catch the event – or prevent opening the panel.

    <script>
    function devToolsOpened(e){
        alert("devtools opened");
        // uncomment to prevent opening dev.tools:
        // e.preventDefault();
    }
    window.addEventListener('keydown', function(e) {
    
        if (
            // CMD + Alt + I (Chrome, Firefox, Safari)
            e.metaKey == true && e.altKey == true && e.keyCode == 73 ||
            // CMD + Alt + J (Chrome)
            e.metaKey == true && e.altKey == true && e.keyCode == 74 ||
            // CMD + Alt + C (Chrome)
            e.metaKey == true && e.altKey == true && e.keyCode == 67 ||
            // CMD + Shift + C (Chrome)
            e.metaKey == true && e.shiftKey == true && e.keyCode == 67 ||
            // Ctrl + Shift + I (Chrome, Firefox, Safari, Edge)
            e.ctrlKey == true && e.shiftKey == true && e.keyCode == 73 ||
            // Ctrl + Shift + J (Chrome, Edge)
            e.ctrlKey == true && e.shiftKey == true && e.keyCode == 74 ||
            // Ctrl + Shift + C (Chrome, Edge)
            e.ctrlKey == true && e.shiftKey == true && e.keyCode == 67 ||
            // F12 (Chome, Firefox, Edge)
            e.keyCode == 123 ||
            // CMD + Alt + U, Ctrl + U (View source: Chrome, Firefox, Safari, Edge)
            e.metaKey == true && e.altKey == true && e.keyCode == 85 ||
            e.ctrlKey == true && e.keyCode == 85
            ){
                devToolsOpened(e);
        }
    });
    </script>
    

    Keyboard shortcuts to open Developer Tools:

    Reply

Leave a Comment