Call javascript function after script is loaded

Question

I have a html page where I am appending html at dynamically through a javascript like below

<script type="text/javascript" src="/myapp/htmlCode"></script>

I want to call a js function e.g. loadedContent(); once the above script adds dynamic html.

Can someone help me how I can do that?

Answer 1

you can achieve this without using head.js javascript.

function loadScript( url, callback ) {
  var script = document.createElement( "script" )
  script.type = "text/javascript";
  if(script.readyState) {  // only required for IE <9
    script.onreadystatechange = function() {
      if ( script.readyState === "loaded" || script.readyState === "complete" ) {
        script.onreadystatechange = null;
        callback();
      }
    };
  } else {  //Others
    script.onload = function() {
      callback();
    };
  }

  script.src = url;
  document.getElementsByTagName( "head" )[0].appendChild( script );
}


// call the function...
loadScript(pathtoscript, function() {
  alert('script ready!'); 
});

Answer 2

I had the same problem... My solution (without jQuery) :

<script onload="loadedContent();" src ="/myapp/myCode.js"  ></script>

Answer 3

If you're reading this post in 2021, probably you're more used to Promises. A more modern approach is preferable if either all your target browsers support ES6 or you are using a polyfill.

This solution works like @JaykeshPatel answer, but it's based on Promises:

// definition
function loadScript(scriptUrl) {
  const script = document.createElement('script');
  script.src = scriptUrl;
  document.body.appendChild(script);
  
  return new Promise((res, rej) => {
    script.onload = function() {
      res();
    }
    script.onerror = function () {
      rej();
    }
  });
}

// use
loadScript('http://your-cdn/jquery.js')
  .then(() => {
    console.log('Script loaded!');
  })
  .catch(() => {
    console.error('Script loading failed! Handle this error');
  });

You can pass some contextual variables in arguments of the res callback, or if your library imported some global symbol, you can reference it there.

For example, since jQuery introduces the $ global symbol, you can call res($) and create a local scope for it (perfect if you are using TypeScript and you don't want to declare a module variable in each file, in this way you can write const $ = await loadScript(..)).

If you don't mean to pass any argument, you can just shorten your code like this:

script.onload = res;
script.onerror = rej;

Answer 4

try something like this

var script = document.createElement('script');

if(script.readyState) {  //IE
script.onreadystatechange = function() {
  if ( script.readyState === "loaded" || script.readyState === "complete" ) {
    script.onreadystatechange = null;
    alert(jQuery);
  }
};
 } else{//others
script.onload = function() {
  alert(jQuery); 
}
}
script.src = "http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.js"
document.documentElement.appendChild(script);

Answer 5

actually you could just put the loadedContent() as the last line of the script you're loading (which is kind of the concept behind JSONP)

Answer 6

My answer is an extension of the Jaykesh Patel answer. I've implemented this code in order to load multiple javascript. Hope this helps someone:

// RECURSIVE LOAD SCRIPTS
function load_scripts( urls, final_callback, index=0 )
{
    if( typeof urls[index+1] === "undefined" )
    {
        load_script( urls[index], final_callback );
    }
    else
    {
        load_script( urls[index], function() {
            load_scripts( urls, final_callback, index+1 );
        } );
    }
}

// LOAD SCRIPT
function load_script( url, callback )
{
    var script = document.createElement( "script" );
    script.type = "text/javascript";
    if(script.readyState) // IE
    {
        script.onreadystatechange = function()
        {
            if ( script.readyState === "loaded" || script.readyState === "complete" )
            {
                script.onreadystatechange = null;
                callback();
            }
        };
    }
    else // Others
    {  
        script.onload = function() { callback(); };
    }
    script.src = url;
    document.getElementsByTagName( "head" )[0].appendChild( script );
    debug("javascript included: "+url);
}

// EXAMPLE  
var main = function()
{
    console.log("main function executed");
}
var js = [ "path/to/script-1", "path/to/script-2", "path/to/script-3" ];
load_scripts( js, main );

Answer 7

Check out head.js. It will achieve what you're after, providing callbacks when your file(s) have successfully loaded and executed.

Answer 8

  $.getScript("your script",function () {
      "your action";
  });