Executing <script> elements inserted with .innerHTML


I've got a script that inserts some content into an element using innerHTML.

The content could for example be:

<script type="text/javascript">alert('test');</script>
<strong>test</strong>

Problem is that the code inside the <script> tag doesn't get executed. I googled it a bit but there were no apparent solutions. If I inserted the content using jQuery $(element).append(content);the script parts got eval'd before being injected into the DOM.

Has anyone got a snippet of code that executes all the <script> elements? The jQuery code was a bit complex so I couldn't really figure out how it was done.

Edit:

By peeking into the jQuery code I've managed to figure out how jQuery does it, which resulted in the following code:

Demo:
<div id="element"></div>

<script type="text/javascript">
  function insertAndExecute(id, text)
  {
    domelement = document.getElementById(id);
    domelement.innerHTML = text;
    var scripts = [];

    ret = domelement.childNodes;
    for ( var i = 0; ret[i]; i++ ) {
      if ( scripts && nodeName( ret[i], "script" ) && (!ret[i].type || ret[i].type.toLowerCase() === "text/javascript") ) {
            scripts.push( ret[i].parentNode ? ret[i].parentNode.removeChild( ret[i] ) : ret[i] );
        }
    }

    for(script in scripts)
    {
      evalScript(scripts[script]);
    }
  }
  function nodeName( elem, name ) {
    return elem.nodeName && elem.nodeName.toUpperCase() === name.toUpperCase();
  }
  function evalScript( elem ) {
    data = ( elem.text || elem.textContent || elem.innerHTML || "" );

    var head = document.getElementsByTagName("head")[0] || document.documentElement,
    script = document.createElement("script");
    script.type = "text/javascript";
    script.appendChild( document.createTextNode( data ) );
    head.insertBefore( script, head.firstChild );
    head.removeChild( script );

    if ( elem.parentNode ) {
        elem.parentNode.removeChild( elem );
    }
  }

  insertAndExecute("element", "<scri"+"pt type='text/javascript'>document.write('This text should appear as well.')</scr"+"ipt><strong>this text should also be inserted.</strong>");
</script>

The OP's script doesn't work in IE 7. With help from SO, here's a script that does:

exec_body_scripts: function(body_el) {
  // Finds and executes scripts in a newly added element's body.
  // Needed since innerHTML does not run scripts.
  //
  // Argument body_el is an element in the dom.

  function nodeName(elem, name) {
    return elem.nodeName && elem.nodeName.toUpperCase() ===
              name.toUpperCase();
  };

  function evalScript(elem) {
    var data = (elem.text || elem.textContent || elem.innerHTML || "" ),
        head = document.getElementsByTagName("head")[0] ||
                  document.documentElement,
        script = document.createElement("script");

    script.type = "text/javascript";
    try {
      // doesn't work on ie...
      script.appendChild(document.createTextNode(data));      
    } catch(e) {
      // IE has funky script nodes
      script.text = data;
    }

    head.insertBefore(script, head.firstChild);
    head.removeChild(script);
  };

  // main section of function
  var scripts = [],
      script,
      children_nodes = body_el.childNodes,
      child,
      i;

  for (i = 0; children_nodes[i]; i++) {
    child = children_nodes[i];
    if (nodeName(child, "script" ) &&
      (!child.type || child.type.toLowerCase() === "text/javascript")) {
          scripts.push(child);
      }
  }

  for (i = 0; scripts[i]; i++) {
    script = scripts[i];
    if (script.parentNode) {script.parentNode.removeChild(script);}
    evalScript(scripts[i]);
  }
};

@phidah... Here is a very interesting solution to your problem: http://24ways.org/2005/have-your-dom-and-script-it-too

So it would look like this instead:

<img src="empty.gif" onload="alert('test');this.parentNode.removeChild(this);" />


Here's a shorter, more efficient script that also works for scripts with the src property:

function insertAndExecute(id, text) {
    document.getElementById(id).innerHTML = text;
    var scripts = Array.prototype.slice.call(document.getElementById(id).getElementsByTagName("script"));
    for (var i = 0; i < scripts.length; i++) {
        if (scripts[i].src != "") {
            var tag = document.createElement("script");
            tag.src = scripts[i].src;
            document.getElementsByTagName("head")[0].appendChild(tag);
        }
        else {
            eval(scripts[i].innerHTML);
        }
    }
}

Note: whilst eval may cause a security vulnerability if not used properly, it is much faster than creating a script tag on the fly.


You should not use the innerHTML property but rather the appendChild method of the Node: a node in a document tree [HTML DOM]. This way you are able to later call your injected code.

Make sure that you understand that node.innerHTML is not the same as node.appendChild. You might want to spend some time on the Javascript Client Reference for more details and the DOM. Hope the following helps...

Sample injection works:

<html>
<head>
<title>test</title>
<script language="javascript" type="text/javascript">
    function doOnLoad(){
        addScript('inject',"function foo(){ alert('injected'); }");
    }


    function addScript(inject,code){
        var _in = document.getElementById('inject');
        var scriptNode = document.createElement('script');
        scriptNode.innerHTML = code;
        _in.appendChild(scriptNode);
    }

</script>
</head>
<body onload="doOnLoad();">
    <div id="header">some content</div>
    <div id="inject"></div>
    <input type="button" onclick="foo(); return false;" value="Test Injected" />
</body>
</html>

regards,


Simplified ES6 version of @joshcomley's answer with an example.

No JQuery, No library, No eval, No DOM change, Just pure Javascript.

http://plnkr.co/edit/MMegiu?p=preview

var setInnerHTML = function(elm, html) {
  elm.innerHTML = html;
  Array.from(elm.querySelectorAll("script")).forEach( oldScript => {
    const newScript = document.createElement("script");
    Array.from(oldScript.attributes)
      .forEach( attr => newScript.setAttribute(attr.name, attr.value) );
    newScript.appendChild(document.createTextNode(oldScript.innerHTML));
    oldScript.parentNode.replaceChild(newScript, oldScript);
  });
}

Usage

$0.innerHTML = HTML;    // does *NOT* run <script> tags in HTML
setInnerHTML($0, HTML); // does run <script> tags in HTML

Try this snippet:

function stripAndExecuteScript(text) {
    var scripts = '';
    var cleaned = text.replace(/<script[^>]*>([\s\S]*?)<\/script>/gi, function(){
        scripts += arguments[1] + '\n';
        return '';
    });

    if (window.execScript){
        window.execScript(scripts);
    } else {
        var head = document.getElementsByTagName('head')[0];
        var scriptElement = document.createElement('script');
        scriptElement.setAttribute('type', 'text/javascript');
        scriptElement.innerText = scripts;
        head.appendChild(scriptElement);
        head.removeChild(scriptElement);
    }
    return cleaned;
};


var scriptString = '<scrip' + 't + type="text/javascript">alert(\'test\');</scr' + 'ipt><strong>test</strong>';
document.getElementById('element').innerHTML = stripAndExecuteScript(scriptString);

function insertHtml(id, html)  
{  
   var ele = document.getElementById(id);  
   ele.innerHTML = html;  
   var codes = ele.getElementsByTagName("script");   
   for(var i=0;i<codes.length;i++)  
   {  
       eval(codes[i].text);  
   }  
}  

It works in Chrome in my project


A solution without using "eval":

var setInnerHtml = function(elm, html) {
  elm.innerHTML = html;
  var scripts = elm.getElementsByTagName("script");
  // If we don't clone the results then "scripts"
  // will actually update live as we insert the new
  // tags, and we'll get caught in an endless loop
  var scriptsClone = [];
  for (var i = 0; i < scripts.length; i++) {
    scriptsClone.push(scripts[i]);
  }
  for (var i = 0; i < scriptsClone.length; i++) {
    var currentScript = scriptsClone[i];
    var s = document.createElement("script");
    // Copy all the attributes from the original script
    for (var j = 0; j < currentScript.attributes.length; j++) {
      var a = currentScript.attributes[j];
      s.setAttribute(a.name, a.value);
    }
    s.appendChild(document.createTextNode(currentScript.innerHTML));
    currentScript.parentNode.replaceChild(s, currentScript);
  }
}

This essentially clones the script tag and then replaces the blocked script tag with the newly generated one, thus allowing execution.


scriptNode.innerHTML = code didn't work for IE. The only thing to do is replace with scriptNode.text = code and it work fine


It's easier to use jquery $(parent).html(code) instead of parent.innerHTML = code:

var oldDocumentWrite = document.write;
var oldDocumentWriteln = document.writeln;
try {
    document.write = function(code) {
        $(parent).append(code);
    }
    document.writeln = function(code) {
        document.write(code + "<br/>");
    }
    $(parent).html(html); 
} finally {
    $(window).load(function() {
        document.write = oldDocumentWrite
        document.writeln = oldDocumentWriteln
    })
}

This also works with scripts that use document.write and scripts loaded via src attribute. Unfortunately even this doesn't work with Google AdSense scripts.


Just do:

document.body.innerHTML = '<img src="../images/loaded.gif" alt="" onload="alert(\'test\');this.parentNode.removeChild(this);" />';

You may take a look at this post. The code might look like this:

var actualDivToBeUpdated = document.getElementById('test');
var div = document.createElement('div');
div.innerHTML = '<script type="text/javascript">alert("test");<\/script>';
var children = div.childNodes;
actualDivToBeUpdated.innerHTML = '';
for(var i = 0; i < children.length; i++) {
    actualDivToBeUpdated.appendChild(children[i]);
}

Thanks to Larry's script, which worked perfectly well in IE10, this is what I've used:

$('#' + id)[0].innerHTML = result;
$('#' + id + " script").each(function() { this.text = this.text || $(this).text();} );

Try function eval().

data.newScript = '<script type="text/javascript">//my script...</script>'
var element = document.getElementById('elementToRefresh');
element.innerHTML = data.newScript;
eval(element.firstChild.innerHTML);

This is a real example from a project that i am developing. Thanks to this post


Extending off of Larry's. I made it recursively search the entire block and children nodes.
The script now will also call external scripts that are specified with src parameter. Scripts are appended to the head instead of inserted and placed in the order they are found. So specifically order scripts are preserved. And each script is executed synchronously similar to how the browser handles the initial DOM loading. So if you have a script block that calls jQuery from a CDN and than the next script node uses jQuery... No prob! Oh and I tagged the appended scripts with a serialized id based off of what you set in the tag parameter so you can find what was added by this script.

exec_body_scripts: function(body_el, tag) {
    // Finds and executes scripts in a newly added element's body.
    // Needed since innerHTML does not run scripts.
    //
    // Argument body_el is an element in the dom.

    function nodeName(elem, name) {
        return elem.nodeName && elem.nodeName.toUpperCase() ===
              name.toUpperCase();
    };

    function evalScript(elem, id, callback) {
        var data = (elem.text || elem.textContent || elem.innerHTML || "" ),
            head = document.getElementsByTagName("head")[0] ||
                      document.documentElement;

        var script = document.createElement("script");
        script.type = "text/javascript";
        if (id != '') {
            script.setAttribute('id', id);
        }

        if (elem.src != '') {
            script.src = elem.src;
            head.appendChild(script);
            // Then bind the event to the callback function.
            // There are several events for cross browser compatibility.
            script.onreadystatechange = callback;
            script.onload = callback;
        } else {
            try {
                // doesn't work on ie...
                script.appendChild(document.createTextNode(data));      
            } catch(e) {
                // IE has funky script nodes
                script.text = data;
            }
            head.appendChild(script);
            callback();
        }
    };

    function walk_children(node) {
        var scripts = [],
          script,
          children_nodes = node.childNodes,
          child,
          i;

        if (children_nodes === undefined) return;

        for (i = 0; i<children_nodes.length; i++) {
            child = children_nodes[i];
            if (nodeName(child, "script" ) &&
                (!child.type || child.type.toLowerCase() === "text/javascript")) {
                scripts.push(child);
            } else {
                var new_scripts = walk_children(child);
                for(j=0; j<new_scripts.length; j++) {
                    scripts.push(new_scripts[j]);
                }
            }
        }

        return scripts;
    }

    var i = 0;
    function execute_script(i) {
        script = scripts[i];
        if (script.parentNode) {script.parentNode.removeChild(script);}
        evalScript(scripts[i], tag+"_"+i, function() {
            if (i < scripts.length-1) {
                execute_script(++i);
            }                
        });
    }

    // main section of function
    if (tag === undefined) tag = 'tmp';

    var scripts = walk_children(body_el);

    execute_script(i);
}

Try this, it works for me on Chrome, Safari & Firefox:

var script = document.createElement('script');
script.innerHTML = 'console.log("hi")';
document.body.appendChild(script); 
--> logs "hi"

One thing to note though, is that the following div-nested script will NOT run:

var script = document.createElement('div');
script.innerHTML = '<script>console.log("hi")</script>';
document.body.appendChild(script);
--> doesn't log anything

For a script to run it has to be created as a node then appended as a child. You can even append a script inside a previously injected div & it will run (I've run into this before when trying to get ad server code to work):

var div = document.createElement('div');
div.id = 'test-id';
document.body.appendChild(div);
var script = document.createElement('script');
script.innerHTML = 'console.log("hi")';
document.getElementById('test-id').appendChild(script);
--> logs "hi"

Expending the answer of Lambder

document.body.innerHTML = '<img src="../images/loaded.gif" alt="" > onload="alert(\'test\');this.parentNode.removeChild(this);" />';

You can use base64 image to create and load your script

<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAAZdEVYdFNvZnR3YXJlAHBhaW50Lm5ldCA0LjAuMjHxIGmVAAAADUlEQVQYV2P4//8/AwAI/AL+iF8G4AAAAABJRU5ErkJggg=="
    onload="var script = document.createElement('script');  script.src = './yourCustomScript.js'; parentElement.append(script);" />

Or if you have a Iframe you can use it instead

<iframe src='//your-orginal-page.com' style='width:100%;height:100%'
    onload="var script = document.createElement('script');  script.src = './your-coustom-script.js'; parentElement.append(script);"
    frameborder='0'></iframe>

I needed something similar, but needed the script to remain or be re-created in the same spot as the original script, since my script targets the location of the script tag in the DOM to create/target elements. I also made the script recursive to make sure it also works if it is more than one level down.

NOTE: I use const here, if you have a older browser, just use var.

    window.exec_body_scripts = function(body_el) {
        // ref: https://stackoverflow.com/questions/2592092/executing-script-elements-inserted-with-innerhtml based on Larry K's answer
        // Finds and executes scripts in a newly added element's body.
        // Needed since innerHTML does not run scripts.
        //
        // Argument body_el is an element in the dom.
        const
            type__Js = 'text/javascript',
            tagName__Script = 'script',
            tagName__Script__Upper = tagName__Script.toUpperCase();
        var scripts = [], script, i;
        function evalScript(elem) {
            var parent = elem.parentNode,
                data = (elem.text || elem.textContent || elem.innerHTML || ""),
                script = document.createElement(tagName__Script);

            script.type = type__Js;
            try {
                // doesn't work on ie...
                script.appendChild(document.createTextNode(data));
            } catch (e) {
                // IE has funky script nodes
                script.text = data;
            }
            // Make sure to re-insert the script at the same position
            // to make sure scripts that target their position
            // in the DOM function as expected.
            var parent = elem.parentNode;
            parent.insertBefore(script, elem);
            parent.removeChild(elem);
        };
        // Get all scripts (recursive)
        if (typeof (document.querySelectorAll) !== typeof (void 0)) {
            document.querySelectorAll('script').forEach((scr) => { if (!scr.type || scr.type.toLowerCase() === type__Js) scripts.push(scr); });
        }
        else {
            var children_nodes = body_el.childNodes, child;
            for (i = 0; children_nodes[i]; i++) {
                child = children_nodes[i];
                if (
                    child.nodeName
                    &&
                    child.nodeName.toUpperCase() === tagName__Script__Upper
                    &&
                    (
                        !child.type
                        ||
                        child.type.toLowerCase() === type__Js
                    )
                ) {
                    scripts.push(child);
                }
                // Recursive call
                window.exec_body_scripts(child);
            }
        }
        for (i = 0; scripts[i]; i++) {
            evalScript(scripts[i]);
        }
    };

Here is my solution in a recent project.

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Sample</title>
</head>
<body>
<h1 id="hello_world">Sample</h1>
<script type="text/javascript">
 var div = document.createElement("div");
  var t = document.createElement('template');
  t.innerHTML =  "Check Console tab for javascript output: Hello world!!!<br/><script type='text/javascript' >console.log('Hello world!!!');<\/script>";
  
  for (var i=0; i < t.content.childNodes.length; i++){
    var node = document.importNode(t.content.childNodes[i], true);
    div.appendChild(node);
  }
 document.body.appendChild(div);
</script>
 
</body>
</html>


Made this new helper function in TypeScript, maybe someone will appreciate it. If you remove type declaration from script parameter it will just be plain JS.

const evalPageScripts = () => {
  const scripts = document.querySelectorAll('script');

  scripts.forEach((script: HTMLScriptElement) => {
    const newScript = document.createElement('script');
    newScript.type = 'text/javascript';
    newScript.src = script.src;

    if (script.parentNode) {
      script.parentNode.removeChild(script);
    }

    return document.body.appendChild(newScript);
  })
};

export default evalPageScripts;