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I found the following JS function that determines whether the connected device is mobile or desktop. It works but if I have an open window of Chrome Developer Tools it always returns false.

function checkDevice(){
    /* true = desktop  false = mobile */

    var check = true;
        (function(a){
          if(/(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|iris|kindle|lge |maemo|midp|mmp|mobile.+firefox|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows ce|xda|xiino/i.test(a)||/1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-/i.test(a.substr(0,4)))
        check = false;
       })(navigator.userAgent||navigator.vendor||window.opera);

       return check; //check
}
luiscla27
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DCR
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  • Probably this happens because you are opening developer tools with mobile emulation enabled. – Elias Soares Jun 18 '22 at 02:37
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    That script is amazing - it must date back to at least 2005-ish - why else is AvantGo mentioned? – Dai Jun 18 '22 at 02:37
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    Anyway, you should not be using `navigator.userAgent` - you should be using `userAgentData.mobile`: https://web.dev/migrate-to-ua-ch/ – Dai Jun 18 '22 at 02:38
  • There's a tool tip for down voting questions. It says "This question does not show any research effort, it is unclear or not useful." So there you go. – Ouroborus Jun 18 '22 at 02:39
  • Did you log the value of `navigator.userAgent` with and without devtools open? That should tell you the reason. – Bergi Jun 18 '22 at 02:49
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    @Dai What's even worse, it's using the deprecated `a.substr(0,4)` method - and you will never match `android` or `avantgo` or `blackberry` etc against a for-letter string… Not to mention the amazing use of an IIFE to mutate a closed-over variable… A real gem. – Bergi Jun 18 '22 at 02:51
  • @Bergi do you have a suggestion for a better way to detect desktop or mobile? Also, how exactly do you log the value of navigator.userAgent? – DCR Jun 19 '22 at 00:07
  • @DCR to fix the mentioned issues, see [here](https://stackoverflow.com/q/3514784/1048572) or [there](https://stackoverflow.com/q/11381673/1048572). But really, you *don't* detect desktop or mobile (or tv, or tablet, etc). You decide which feature you care about, and test for that. – Bergi Jun 19 '22 at 04:30
  • As for logging, just `console.log` it. Or `alert` it. Or print it into the page. Or something. – Bergi Jun 19 '22 at 04:30

1 Answers1

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The function you show checks against the userAgent value. Chrome Developer Tools can override that value in tab "Network Conditions".

Just make sure that your userAgent is not being override: enter image description here

luiscla27
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