一旦满足条件，异步调用函数？

Question

I'm injecting jQuery and a few jQuery plugins into a page via a bookmarklet. The plugins must be started after jQuery is finished loading. Otherwise I'll get an error, "jQuery is not defined". So I need a way to delay it until then.

Currently I'm using setInterval. It keeps looping until the condition is satisfied, then creates the next script.

Function Calls

injectScript('https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js');
injectScript('http://www.jnathanson.com/blog/client/jquery/heatcolor/jquery.heatcolor.0.0.1.pack.js', function(){return typeof jQuery != 'undefined'});

Function Definitions

function injectScript(src, dependency){
    /* Description: creates a new script within the DOM         */

    /* Syntax:                                                  */

    /* src                                                      */
    /*       contains a string to the link location of          */
    /*       the script.                                        */

    /* dependency                                               */
    /*       a function that returns true when all dependent    */
    /*       scripts are finished loading.                      */


    scriptLoad.total++;
    dependency = dependency || function(){return true};




    var depenLoop = setInterval(function(){ /* Wait for dependencies to finish loading, then create the script */
        if(dependency()){
            clearInterval(depenLoop);

            var script    = document.createElement('script');
            script.onload = function(){ scriptLoad.ready++; };  /* onload must be set before src, otherwise src could */
            script.src    = src;                                /* finish early and onload would never fire.          */
            document.body.appendChild(script);

        }/*end if*/
    }, 100);/*loop*/
}/*end function*/

Messy, but this code works. However I'm looking for a better solution. Is any other way to do this without using setInterval and with pure JS?

Answer 1

Use

<script src="jquery.js"></script>
<script>
$(function(){
    // Code to execute after jQuery has loaded
});
</script>
</body>

Place the <script> tags that include jQuery at the end of the document body, and then add the code for your plugins after it.