Develop Reference

Dynamically add javascript script to page with code not src

I am trying to figure out how to inject this script into a site using Tampermonkey. Here is what I have so far but the onBrazeSdkLoaded event is never being called so I don't think its being inserted correctly. I have tried a few iterations but no luck. To reference the exact script I am trying to include here is the link to the public docs.
https://www.braze.com/docs/developer_guide/platform_integration_guides/web/initial_sdk_setup/#install-gtm
const script = document.createElement("script");
var code = document.createTextNode(`+function(a,p,P,b,y){a.braze={};a.brazeQueue=[];for(var s="BrazeSdkMetadata DeviceProperties Card Card.prototype.dismissCard Card.prototype.removeAllSubscriptions Card.prototype.removeSubscription Card.prototype.subscribeToClickedEvent Card.prototype.subscribeToDismissedEvent Card.fromContentCardsJson Banner CaptionedImage ClassicCard ControlCard ContentCards ContentCards.prototype.getUnviewedCardCount Feed Feed.prototype.getUnreadCardCount ControlMessage InAppMessage InAppMessage.SlideFrom InAppMessage.ClickAction InAppMessage.DismissType InAppMessage.OpenTarget InAppMessage.ImageStyle InAppMessage.Orientation InAppMessage.TextAlignment InAppMessage.CropType InAppMessage.prototype.closeMessage InAppMessage.prototype.removeAllSubscriptions InAppMessage.prototype.removeSubscription InAppMessage.prototype.subscribeToClickedEvent InAppMessage.prototype.subscribeToDismissedEvent InAppMessage.fromJson FullScreenMessage ModalMessage HtmlMessage SlideUpMessage User User.Genders User.NotificationSubscriptionTypes User.prototype.addAlias User.prototype.addToCustomAttributeArray User.prototype.addToSubscriptionGroup User.prototype.getUserId User.prototype.incrementCustomUserAttribute User.prototype.removeFromCustomAttributeArray User.prototype.removeFromSubscriptionGroup User.prototype.setCountry User.prototype.setCustomLocationAttribute User.prototype.setCustomUserAttribute User.prototype.setDateOfBirth User.prototype.setEmail User.prototype.setEmailNotificationSubscriptionType User.prototype.setFirstName User.prototype.setGender User.prototype.setHomeCity User.prototype.setLanguage User.prototype.setLastKnownLocation User.prototype.setLastName User.prototype.setPhoneNumber User.prototype.setPushNotificationSubscriptionType InAppMessageButton InAppMessageButton.prototype.removeAllSubscriptions InAppMessageButton.prototype.removeSubscription InAppMessageButton.prototype.subscribeToClickedEvent automaticallyShowInAppMessages destroyFeed hideContentCards showContentCards showFeed showInAppMessage toggleContentCards toggleFeed changeUser destroy getDeviceId initialize isPushBlocked isPushPermissionGranted isPushSupported logCardClick logCardDismissal logCardImpressions logContentCardImpressions logContentCardsDisplayed logCustomEvent logFeedDisplayed logInAppMessageButtonClick logInAppMessageClick logInAppMessageHtmlClick logInAppMessageImpression logPurchase openSession requestPushPermission removeAllSubscriptions removeSubscription requestContentCardsRefresh requestFeedRefresh requestImmediateDataFlush enableSDK isDisabled setLogger setSdkAuthenticationSignature addSdkMetadata disableSDK subscribeToContentCardsUpdates subscribeToFeedUpdates subscribeToInAppMessage subscribeToSdkAuthenticationFailures toggleLogging unregisterPush wipeData handleBrazeAction".split(" "),i=0;i<s.length;i++){for(var m=s[i],k=a.braze,l=m.split("."),j=0;j<l.length-1;j++)k=k[l[j]];k[l[j]]=(new Function("return function "+m.replace(/\./g,"_")+"(){window.brazeQueue.push(arguments); return true}"))()}window.braze.getCachedContentCards=function(){return new window.braze.ContentCards};window.braze.getCachedFeed=function(){return new window.braze.Feed};window.braze.getUser=function(){return new window.braze.User};(y=p.createElement(P)).type='text/javascript';
y.src='https://js.appboycdn.com/web-sdk/4.2/braze.min.js';
y.async=1;(b=p.getElementsByTagName(P)[0]).parentNode.insertBefore(y,b)`);
script.text = code;
document.head.appendChild(script);
script.onload = onBrazeSdkLoaded;

A load event fires when a resource has been loaded from an external source.
Since your script is getting its program from a text node inside the script element, instead of from a URL assigned to the src attribute, there is no external source.
Consequently, there is no load event.
If you want onBrazeSdkLoaded to fire when the script you create on line 1 has loaded, then just include onBrazeSdkLoaded() in the string you assign to code.
If you want it to fire when https://js.appboycdn.com/web-sdk/4.2/braze.min.js loads, then you need to:
Ensure it is in the global scope
Write code that assigns it to y.onload inside the string you assign to code
Fix the syntax error(s) in the JS in that string

Overwriting the URL at runtime through JS in IE11

I have a page that loads some external script (Ex: abc.com/test.js) by default.
I will create a bookmarklet that will overwrite that external script with a new URL (Ex: def.com/newTest.js), when the page is loading.
Can any body let me know on how to overwrite the URL at run time in IE11 ...
Any help would be highly appreciated.

Something like following (you can merge it to the one line for bookmarklet):
var s = document.querySelector("script[src='abc.com/test.js']");
s.parentNode.removeChild(s);
s = document.createElement('script');
s.src = "def.com/newTest.js";
document.body.appendChild(s)

jQuery Version:
$(document).on('ready', function(){
$('head').find('script[src="abc.com/test.js"]').attr('src','def.com/newTest.js');
});

Can JavaScript access it's own source url?

Suppose I'm embedding a javascript in HTML page:
<script type="text/javascript" src="www.mydomain.com/script.js?var1=abc&var2=def"></script>
Is there a way I can get the src url inside the script and extract the params?

Given that you are using a regular script element in the HTML source, you can just get the last script element in the document. Since script elements are (in the absence of attributes that you aren't using in your example) blocking, no more will be added to the document until this one has been executed.
var scripts = document.getElementsByTagName('script');
var last_script = scripts[scripts.length - 1];
var url = script.src;
This won't work if you dynamically add a script element before the last script using DOM.

this little hack uses error handling to find the location of external scripts from within:
(function(){ // script filename setter, leaves window.__filename set with active script URL.
if(self.attachEvent){
function fn(e,u){self.__filename=u;}
attachEvent("onerror",fn);
setTimeout(function(){detachEvent("onerror", fn)},20);
eval("gehjkrgh3489c()");
}else{
Object.defineProperty( window, "__filename", { configurable: true, get:function __filename(){
try{document.s0m3741ng()}catch(y){
return "http://" +
String(y.fileName || y.file || y.stack || y + '')
.split(/:\d+:\d+/)[0].split("http://")[1];
}
}})//end __filename
}//end if old IE?
}());
it sets a global "__filename" property when run, so atop an external script, the __filename is in effect for the execution of the whole script.
i strongly prefer to sniff url parts from scr attributes, but this works in most browsers and without knowing the URL ahead of time.

I don't think there is a property already inside the script that points to this url.
From the script, you can read the DOM. So you can lookup the script tag and inspect its src attribute, but if you got multiple scripts (or the DOM was modified), you cannot really know for sure which one it is.
I assume it is for checking input. So to solve this, you can eiter:
Render the script through a server side script (PHP), and let it output variables. Disadvantage: eats more server resources and makes caching a bitch.
Just get parameter from all the scripts loading from your domain. Maybe it doesn't matter much, or you have only one script anyway. Disadvantage: In this case this is possible, but not very reliable and resistant to changes.
My preferred: Add the variables to the script tag (actually, to another script tag) to make them available directly in Javascript, rather than parsing the script url.
Like this:
<script type="text/javascript">
var1 = 'abc';
var2 = 'def';
</script>
<script type="text/javascript" src="www.mydomain.com/script.js"></script>

Here are two other solutions that will work no matter how the script is loaded (even if they are loaded dynamically or with async or defer attributes):
Put an id on the script tag.
<script id="myscript" type="text/javascript" src="www.mydomain.com/script.js?var1=abc&var2=def"></script>
Then, you can find it with the id:
$("#myscript").attr("src")
Or second, if you know the filename, you can search for any script tag that contains that filename:
function findScriptTagByFilename(fname) {
$("script").each(function() {
if (this.src.indexOf(fname) !== -1) {
return this.src;
}
});
}
var url = findScriptTagByFilename("/script.js");

How to include jquery.js in another js file?

I want to include jquery.js in myjs.js file. I wrote the code below for this.
var theNewScript=document.createElement("script");
theNewScript.type="text/javascript";
theNewScript.src="http://example.com/jquery.js";
document.getElementsByTagName("head")[0].appendChild(theNewScript);
$.get(myfile.php);
There shows an error on the 5th line that is '$ not defined'. I want to include jquery.js and then want to call $.get() function in myjs.js file. How can I do this?
Please help me

Appending a script tag inside the document head programmatically does not necessarily mean that the script will be available immediately. You should wait for the browser to download that file, parse and execute it. Some browsers fire an onload event for scripts in which you can hookup your logic. But this is not a cross-browser solution. I would rather "poll" for a specific symbol to become available, like this:
var theNewScript = document.createElement("script");
theNewScript.type = "text/javascript";
theNewScript.src = "http://example.com/jquery.js";
document.getElementsByTagName("head")[0].appendChild(theNewScript);
// jQuery MAY OR MAY NOT be loaded at this stage
var waitForLoad = function () {
if (typeof jQuery != "undefined") {
$.get("myfile.php");
} else {
window.setTimeout(waitForLoad, 1000);
}
};
window.setTimeout(waitForLoad, 1000);

The problem is that the script doesn't load instantly, it takes some time for the script file to download into your page and execute (in case of jQuery to define $).
I would recommend you to use HeadJS. then you can do:
head.js("/path/to/jQuery.js", function() {
$.get('myfile.php');
});

Simple answer, Dont. The jQuery file
is very touchy to intruders so dont
try. Joining other files into jQuery
file will often cause errors in the JS
console, PLUS jQuery isn't initialized
until the file is loaded into main
document.
Sorry, scratch that. Didnt quite know what you were doing.
Try this:
var s = document.createElement('script');
s.type = 'text/javascript';
s.async = true;
s.src = 'http://domain.com/jquery.js';
(document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(s);

I used this code before, and it worked:
var t=document;
var o=t.createElement('script');
o=t.standardCreateElement('script');
o.setAttribute('type','text/javascript');
o.setAttribute('src','http://www.example.com/js/jquery-1.3.2.js');
t.lastChild.firstChild.appendChild(o);

Is there a way to refresh just the javascript include while doing development?

While doing development on a .js file I'd like to just refresh that file instead of the entire page to save time. Anyone know of any techniques for this?

Here is a function to create a new script element. It appends an incremented integer to make the URL of the script unique (as Kon suggested) in order to force a download.
var index = 0;
function refreshScript (src) {
var scriptElement = document.createElement('script');
scriptElement.type = 'text/javascript';
scriptElement.src = src + '?' + index++;
document.getElementsByTagName('head')[0].appendChild(scriptElement);
}
Then in the Firebug console, you can call it as:
refreshScript('my_script.js');
You'll need to make sure that the index itself is not part of the script being reloaded!
The Firebug Net panel will help you see whether the script is being downloaded. The response status should be "200 OK" and not "304 Not Modified. Also, you should see the index appended in the query string.
The Firebug HTML panel will help you see whether the script element was appended to the head element.
UPDATE:
Here is a version that uses a timestamp instead of an index variable. As #davyM suggests, it is a more flexible approach:
function refreshScript (src) {
var scriptElement = document.createElement('script');
scriptElement.type = 'text/javascript';
scriptElement.src = src + '?' + (new Date).getTime();
document.getElementsByTagName('head')[0].appendChild(scriptElement);
}
Alexei's points are also well-stated.

I suggest you to use Firebug for this purpose.
See this video, it helped me a lot.
http://encosia.com/2009/09/21/updated-see-how-i-used-firebug-to-learn-jquery/

If you're talking about the unfortunate case of client-side/browser caching of your .js file, then you can simply version your .js file. You can:
Rename the .js file itself (not preferred)
Update the include line to reference yourfile.js?1, yourfile.js?2, etc.. Thus forcing the browser to request the latest version from the server. (preferred)

Unfortunately, you have to refresh the web page to see edits to your JavaScript take place. There is no way that I know of to edit JavaScript in "real-time" and see those edits effect without a refresh.
You can use Firebug to insert new JavaScript, and make real-time changes to DOM objects; but you cannot edit JavaScript that has already been run.

If you just fed up refilling the forms while developing just use form recover extensions like this one https://addons.mozilla.org/ru/firefox/addon/lazarus-form-recovery/