Checking if jquery is loaded using Javascript

Question

I am attempting to check if my Jquery Library is loaded onto my HTML page   I am checking to see if it works  but something is not right   Here is what I have    lt html xmlns  http   www w3 org 1999 xhtml  gt       lt head gt           lt script type  text javascript  src   query-1 6 3 min js  gt  lt  script gt           lt script type  text javascript  gt              document  ready function                 if  jQuery                        jQuery is loaded                  alert  Yeah                    else                     jQuery is not loaded                alert  Doesn t Work                                          lt  script gt

User · Accepted Answer

something is not right  Well  you are using jQuery to check for the presence of jQuery  If jQuery isn t loaded then     won t even run at all and your callback won t execute  unless you re using another library and that library happens to share the same     syntax  Remove your   document  ready    use something like window onload instead   window onload   function         if  window jQuery                 jQuery is loaded           alert  quot Yeah  quot          else              jQuery is not loaded         alert  quot Doesn t Work quot

User · Answer

You can check whether it exists and  if it does not exist  load it dynamically  function loadScript src        return new Promise function  resolve  reject            var s          s   document createElement  script            s src   src          s onload   resolve          s onerror   reject          document head appendChild s                async function load    if   window jQuery       await loadScript  https   cdnjs cloudflare com ajax libs jquery 3 5 1 jquery min js       console log jQuery       load

User · Answer

You can just type  window jQuery in Console   If it return a function e n      Then it is confirmed that the jquery is loaded and working successfully

User · Answer

A quick way is to run a jQuery command in the developer console  On any browser hit F12 and try to access any of the element         sideTab2   css  background-color    yellow

User · Answer

if   undefined     typeof window jQuery           jQuery not present   else          jQuery present

User · Answer

CAUTION  Do not use jQuery to test your jQuery When you are using any of the code provided by other users and if you want to display the message on your window and not on the alert or console log  Then make sure you use javascript and not jquery  Not everyone want to use alert or console log alert  jquery is working    console log  jquery is working     The code below will fail to display the message Because we are using jquery inside the else  how the hell the message displays on your screen if you do not have jquery  if   undefined     typeof window jQuery            selector   appendTo  jquery is NOT working      else           selector   appendTo  jquery is working       Use JavaScript instead if   undefined     typeof window jQuery        document getElementById  selector   innerHTML    quot jquery is NOT working quot     else       document getElementById  selector   innerHTML    quot jquery is working quot

User · Answer

As per this link   if  typeof jQuery     undefined            jQuery IS NOT loaded  do stuff here       there are a few more in comments of the link as well like   if  typeof jQuery     function            or  if  typeof      function             or  if  jQuery        alert  jquery is loaded      else       alert  Not loaded         Hope this covers most of the good ways to get this thing done

User · Answer

Just a small modification that might actually solve the problem   window onload   function        if  window jQuery                jQuery is loaded          alert  Yeah          else       location reload             Instead of   document  Ready function   use window onload   function

User · Answer

You can do this fast on the console-tab when inspecting your webpage   E g         jQuery   If it returns true it means it s loaded

User · Answer

If jQuery is loading asynchronously  you can wait till it is defined  checking for it every period of time    function         var a   setInterval  function             if   typeof window jQuery      undefined                  return                    clearInterval  a             console log   jQuery is loaded        call your function with jQuery instead of this        500            This method can be used for any variable  you are waiting to appear

[javascript] Checking if jquery is loaded using Javascript

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