check if jquery has been loaded then load it if false

Question

Does anyone know how to check if jquery has been loaded  with javascript  then load it if it hasnt been loaded   something like  if  jQuery          load jquery file

User · Answer

You can check if jQuery is loaded or not by many ways such as:

if (typeof jQuery == 'undefined') {

    // jQuery IS NOT loaded, do stuff here.

}

if (typeof jQuery == 'function')
//or
if (typeof $== 'function')

if (jQuery) {
    // This will throw an error in STRICT MODE if jQuery is not loaded, so don't use if using strict mode
    alert("jquery is loaded");
} else {
    alert("Not loaded");
}

if( 'jQuery' in window ) {
    // Do Stuff
}

Now after checking if jQuery is not loaded, you can load jQuery like this:

Although this part has been answered by many in this post but still answering for the sake of completeness of the code

    // This part should be inside your IF condition when you do not find jQuery loaded
    var script = document.createElement('script');
    script.type = "text/javascript";
    script.src = "http://code.jquery.com/jquery-3.3.1.min.js";
    document.getElementsByTagName('head')[0].appendChild(script);

User · Answer

Old post but I made an good solution what is tested on serval places   https   github com CreativForm Load-jQuery-if-it-is-not-already-loaded  CODE    function url  position  callback          default values     url   url     https   ajax googleapis com ajax libs jquery 3 3 1 jquery min js       position   position    0          Check is jQuery exists     if   window jQuery               Initialize  lt head gt          var head   document getElementsByTagName  head   0              Create  lt script gt  element         var script   document createElement  script               Append URL         script src   url             Append type         script type    text javascript              Append script to  lt head gt          head appendChild script              Move script on proper position         head insertBefore script head childNodes position             script onload   function                if typeof callback     function                     callback jQuery                                  else           if typeof callback     function                 callback jQuery                      https   ajax googleapis com ajax libs jquery 1 12 4 jquery min js   5  function          console log            At GitHub is better explanation but generaly this function you can add anywhere in your HTML code and you will initialize jquery if is not already loaded

User · Answer

lt script gt  if  typeof jQuery      undefined            document write   lt scr     ipt type  text javascript  src   https   ajax googleapis com ajax libs jquery 1 11 0 jquery min js  gt  lt  scr     ipt gt        lt  script gt

User · Answer

I am using CDN for my project and as part of fallback handling  i was using below code    lt script type  text javascript  src  https   ajax googleapis com ajax libs jquery 1 9 1 jquery min js  gt  lt  script gt       lt script type  text javascript  gt                  if   typeof jQuery     undefined                          document write unescape   3Cscript src   Responsive Scripts jquery-1 9 1 min js  type  text javascript  3E 3C script 3E                           lt  script gt    Just to verify  i removed CDN reference and execute the code  Its broken and it s never entered into if loop as typeof jQuery is coming as function instead of undefined    This is because of cached older version of jquery 1 6 1 which return function and break my code because i am using jquery 1 9 1  As i need exact version of jquery  i modified code as below    lt script type  text javascript  src  https   ajax googleapis com ajax libs jquery 1 9 1 jquery min js  gt  lt  script gt   lt script type  text javascript  gt              if   typeof jQuery     undefined       jQuery fn jquery     1 9 1                      document write unescape   3Cscript src   Responsive Scripts jquery-1 9 1 min js  type  text javascript  3E 3C script 3E                       lt  script gt

User · Answer

Avoid using  if   jQuery   since IE will return the error  jQuery is  undefined   Instead use  if  typeof jQuery     undefined     lt script type  text javascript  gt  if  typeof jQuery     undefined         var script   document createElement  script        script type    text javascript       script src    http   ajax googleapis com ajax libs jquery 1 11 0 jquery min js       document getElementsByTagName  head   0  appendChild script      lt  script gt    You ll also need to check if the JQuery has loaded after appending it to the header   Otherwise you ll have to wait for the window onload event  which is slower if the page has images   Here s a sample script which checks if the JQuery file has loaded  since you won t have the convenience of being able to use   document  ready function     http   neighborhood org core sample jquery append-to-head htm

User · Answer

var f       gt       if   window jQuery            var e   document createElement  script            e src    https   code jquery com jquery-3 2 1 min js           e onload   function                  jQuery noConflict                console log  jQuery     jQuery fn jquery     injected                        document head appendChild e         else           console log  jQuery     jQuery fn jquery                 f

User · Answer

Even though you may have a head appending it may not work in all browsers  This was the only method I found to work consistently    lt script type  text javascript  gt  if  typeof jQuery     undefined       document write   lt script type  text javascript  src  http   ajax googleapis com ajax libs jquery 1 8 2 jquery min js  gt  lt   script gt                   lt  script gt

User · Answer

Method 1   if  window jQuery             jQuery is loaded     else          jQuery is not loaded     Method 2   if  typeof jQuery     undefined              jQuery is not loaded   else          jQuery is loaded     If jquery js file is not loaded  we can force load it like so   if   window jQuery      var jq   document createElement  script    jq type    text javascript        Path to jquery js file  eg  Google hosted version   jq src     path-to-your jquery min js     document getElementsByTagName  head   0  appendChild jq

User · Answer

Try this     lt script gt    window jQuery    document write   lt script src  js jquery min js  gt  lt   script gt     lt  script gt    This checks if jQuery is available or not  if not it will add one dynamically from path specified   Ref  Simulate an  quot include once quot  for jQuery  OR  include once equivalent for js  Ref  https   raw github com kvz phpjs master functions language include once js  function include once  filename         http   kevin vanzonneveld net          original by  Legaev Andrey          improved by  Kevin van Zonneveld  http   kevin vanzonneveld net           improved by  Michael White  http   getsprink com              input by  Brett Zamir  http   brett-zamir me           bugfixed by  Kevin van Zonneveld  http   kevin vanzonneveld net           bugfixed by  Brett Zamir  http   brett-zamir me       -    depends on  include               note 1  Uses global  php js to keep track of included files  though private static variable in namespaced version             example 1  include once  http   www phpjs org js phpjs  supporters pj test supportfile 2 js               returns 1  true   var cur file         cur file this window location href    1        BEGIN STATIC   try      We can t try to access on window  since it might not exist in some environments  and if we use  this window            we risk adding another copy if different window objects are associated with the namespaced object     php js shared     Will be private static variable in namespaced version or global in non-namespaced          version since we wish to share this across all instances     catch  e        php js shared                END STATIC   if   php js shared includes        php js shared includes   cur file        if   php js shared includes filename         if  this include filename           return true            else       return true        return false

User · Answer

Maybe something like this    lt script gt  if  window jQuery       var script   document createElement  script       script type    text javascript      script src    path to jQuery      document getElementsByTagName  head   0  appendChild script      lt  script gt

[javascript] check if jquery has been loaded, then load it if false

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