How to execute a function when jQuery is loaded?

I'm making a bookmarklet and using jQuery for it (with noConflict). I need to wait for jQuery to load, to execute all the jQuery code.

I know I can check with typeof $ for jQuery, but I'm actually more looking for an event handler. Right now I'm just开发者_C百科 using setTimeout with a delay of 1s, because jQuery is proberly loaded then. I feel this is not a good solution. It's not clean code and relies on jQuery to load in 1s.

Is there any other way to afford this?

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Just for the records, completeness and for those that didn't know: Without an event handler, a good alternative would be to poll for jQuery every X amount of time. Ex:

function is_jquery_here(){
    setTimeout(function(){
      if(window.jQuery){
         my_jquery_code_here();
      } else {
        is_jquery_here();
      }
    }, 300);
}
is_jquery_here();

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Since you say you're appending it dynamically, you could make use of onload:

var elem = document.createElement('script');
elem.onload = function() {
    // script is loaded, you can now do things with jQuery
};
elem.src = 'path to jquery';
document.getElementsByTagName('head')[0].appendChild(elem);

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Not every browser supports .onload for script elements, so if you need cross-browser compatibility, use onreadystatechange as well:

function load( src, callback )
{
  var s,r;
  s = document.createElement('script');
  s.type = 'text/javascript';
  s.src = src;
  s.onload = s.onreadystatechange = function(){
    if ( !r && ( !this.readyState || this.readyState == 'complete' ) )
    {
      r = 1;
      callback();
    }
  };
  document.body.appendChild(s);
}

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If you have jQuery script in the page and you just want to make sure its loaded first, then I'd highly recommend that one

window.onload = function() {
  //.....your jquery code....
};

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Michael is right. You could also use this shorthand

$(function() {
    // Code for on docload here
});