I have two scripts and basically what I want to do is combine them in order to render the result of both in one map.
I already tried to copy/past, but for a reason that I ignore, it's not working (I just start learning so I have basic knowledge in js and gmaps api).
So please before down vote, understand that what I want is just to know if YES or NO there is a way to do such a thing. I tried to search on the net and read Google developer doc but can't find an answer.
Thank you.
It depends on how you use the two scripts. In JavaScript, all scripts you use/import into your html run in the same global scope. So they can access each other's global objects. But keep in mind that the script tags are executed sequentially in the order of appearance.
So:
You can have as many tags as you would like in a document.
The tags are processed as they are encountered.
How to use Script tag:
<script>
// Inline JavaScript code here
</script>
<script src="external.js"></script>
More info:
https://developer.mozilla.org/en/docs/Web/HTML/Element/script
multiple versus single script tags
Related
I'm working on small .js which is going to be embedded on multiple websites, it will be loaded in a classic way - via script tag: <script src="myscript.js"></script> in sites body tag. I cannot add any more scripts to those sites.
I would like to track errors with error tracker such as Sentry, Rollup or HoneyBadger. However, all of them require being loaded with another script tag, most preferred before everything else.
Note: Those services need to load before everything else to catch errors property.
As I cannot add another script tag in the site's code, I need to execute their code inside my script, but before my actual script code.
I tried taking the content of HoneyBadger javascript library and putting it directly inside my file - it worked, however, I feel like it's terrible practice, as their code is written with modern browsers in mind, and mine supports older ones.
Is there any good way in my situation to load their .js externally?
I don't think that would work because of the way honeybadger.js v0.5 parses the script tag to get those attributes--it looks for the script tag in the dom when it's loaded.
Also, we've moved away from using the data- attributes in honeybadger.js v1.0, which was just released. In that version, you must use Honeybadger.configure to set your API key. Take a look at the new docs here:
https://docs.honeybadger.io/lib/javascript/integration/browser.html
I'd recommend going with v1.0, and using Honeybadger.configure for the configuration.
Website that use JS tracking usually use this kind of code :
<script>
(function(h,o,t,j,a,r){
h.hj=h.hj||function(){(h.hj.q=h.hj.q||[]).push(arguments)};
h._hjSettings={hjid:9999,hjsv:5};
a=o.getElementsByTagName('head')[0];
r=o.createElement('script');r.async=1;
r.src=t+h._hjSettings.hjid+j+h._hjSettings.hjsv;
a.appendChild(r);
})(window,document,'//static.hotjar.com/c/hotjar-','.js?sv=');
</script>
In the end, those scripts just add a <script> tag to the <head> of the page, so surely there must be a reason why they're doing it this way.
Is it for ad-blocking bypass reasons ? Wouldn't the generated request be the same as if it was hardcoded in the <head> ?
I'm the chief architect at Hotjar so I'll explain the reasons why we did it in this particular way.
We need to do things before the main script is loaded.
h.hj=h.hj||function(){(h.hj.q=h.hj.q||[]).push(arguments)};
That particular line allows us to store actions to execute once the main script is loaded. It allows for things like hj('trackVirtualPageView', '/url') to be called before our script is loaded.
We can store things like settings as part of the snippet.
h._hjSettings={hjid:9999,hjsv:5};
That could absolutely be added as part of the query string when loading the script. The downside of using that approach is that we would get less optimal caching since it would be impossible for a browser to know that script.js?hjid=1 and script.js?hjid=2 actually loads the same JS file.
What we're doing in the last part is actually just creating a <script async=1> tag and adding it to the <head> which works really well. The reason we're doing it through JS is that we like to make it as easy as possible for our users by only asking them to put code in one place.
There might be an even better to do what we're doing which I'm blissfully unaware of, and in case there is, please reach out and tell me about it! :)
At least part of the answer is that vendors want to load their libraries in a way that does not block page rendering.
If the browser hits a script element it tries to get the script source, and might prevent the page from rendering until the complete script is downloaded. In the bad old days it used to happen that website would show up blank, because the (then synchronous) Google Analytics script could not be downloaded in a timely fashion and stopped the page from rendering. Script injection became an accepted method to make scripts non-blocking.
There are other ways (defer, asynch, etc - for historical interest here is a link to an 2009 article that discusses the issue, because the problem is that old), but script injection is a convenient way to set up a few variables along the way (plus if Google does it it must be the best way, or so seems to be the though process with some companies).
The website I'm working on has hundreds of existing pages, and I want to insert an Autocomplete feature into every page. I don't want to have to put the Javascript <script src=> call into the hundred of pages. The field using the JS is contained in the Nav which is called on every page from a php include, so getting the HTML in is no problem.
There are a few places I think I could put the Javascript in -
1. Either add the Javascript functions to an existing Javascript Script that is called in the header,
2. or even put in the <script> call in an existing php include that calls the $_SESSION and mysql data to everypage, but that is called even before the <!DOCTYPE> declaration, so I don't think I would want to put it there.
3. But, because I would like to keep it in it's own file (In case it needs replacing, tidiness, etc) I want to keep the autocomplete Javascript in it's own file. Would it be ok to put a <script> call inside of an existing <script call>? I hope that is clear.
4. OR, put the <script src> inside the nav.php (which is called on everypage). But I'm not sure how well putting a PHP include inside of a Javascript file would work out.
If anyone has any opinions or advice as to which would work the best, please let me know. Thanks!
Best option is to create jquery plugin and use it where ever required. Dont forget to make proper use of $ or jquery, because it may crash between plugin and script file in which plugin is placed.
In my project I have a load of functions that are used on every page, so I have put these in a single javascript file common.js and have included it in my footer template. My questions is, what is the best way to handle page-specific javscript?
For example, on one of my pages I have a google map. If my map js code is run on a page where I don't have an element with id map_canvas, I get an error.
Method 1: I could write some PHP which echos an additional script tag requesting map.js if and only if I'm on a map page.
Method 2: I could give the <body> of my map page an id of "map_page", then I could write a conditional clause in common.js along the lines of:
if (#map_page exists){
put contents of map.js here
}
The problem with method 1 is that it increases the number of requests to the server.
The problem with method 2 is that it bloats my common javascript file.
Please can somebody explain, which, if any would be the preferred method to do this, or if neither are suitable, what I should do instead?
I have approximately 10 page-specific javascript files to deal with.
Thanks
I would say that simpler is better. On every page, just add a script tag calling map.js. Or, in your common.js, you don't need to paste all of map.js's code. You can just create a new script tag with the js and call map.js like that. I would not recommend the php method. The easiest and simplest, therefore the least likely to be buggy method, is just to add another script tag to the pages that need it. Or if that is not an option, common.js could include this:
if(need map.js){
var mapjs=document.createElement("script");
mapjs.type="text/javascript";
mapjs.src="map.js";
document.body.appendChild(mapjs);
}
When I use google maps, I am interested in its implemention, so I use the firebug to inspect.
Then I found that its javascript loading strategy is rather interesting. Take this page for example:
The overlay example
Then when I open this page first time, the following js are loaded:
https://maps.googleapis.com/maps/api/js?sensor=false
https://maps.gstatic.com/intl/en_us/mapfiles/api-3/9/13b/main.js
https://maps.gstatic.com/cat_js/intl/en_us/mapfiles/api-3/9/13b/%7Bcommon,map,util,poly%7D.js
https://maps.gstatic.com/cat_js/intl/en_us/mapfiles/api-3/9/13b/%7Bonion,geometry%7D.js
But if I refresh the page(use the ctrl+f5), the following js are loaded:
https://maps.googleapis.com/maps/api/js?sensor=false
https://maps.gstatic.com/intl/en_us/mapfiles/api-3/9/13b/main.js
However the page still works, the overlay is drawn in the map. But where is the poly.js and etc?
Also, can anyone tell me how to load the js by components? For exmaple the common util poly in the example.
What should I know when I write the different components?
1. When poly.js loads, it passes a string to google.maps.__gjsload___.
Here's an excerpt:
google.maps.__gjsload__('common', '\'use strict\';var Ai=isNa...
The rest of the file is just the contents of that string.
My hunch is this function probably stores this string in localStorage or sessionStorage so that it only has to be retrieved once.
2. Also, if you want to learn about loading js files as-needed, look into AMD and/or CommonJS:Modules.
A good imlementation of AMD (my preference) is RequireJS.
Update
I did some poking around, and localStorage and sessionStorage do not appear to be being used on this page. I also can't duplicate your results. In Firebug, poly.js always loads for me. There may be some magic happening somewhere, but I don't see it.
However, it's entirely possible to store a string in localStorage and sessionStorage for retrieval without having to make an extra js call.
Also,any one can tell me how to load the js by components?
this touches on the topic of asynchronous javascript file loading. if you've ever used a language that has a way to "include" a file at any point in a script, you'll understand that javascript does not have this capability. because of that, there is this whole paradigm of "aysnc javascript addition" via script tag injection.
script tag injection: you dynamically make a script tag, and set its source to the file you need, and insert that tag into the DOM, and voila, a new file has been loaded and executed. With javascript heavy applications, this is common, especially when loading third party applications. Google does it alllll the time, just check out google analytics' include script for a good example of this.
Now, since this is a touchy and delicate type of coding to do, some "javascript component / module / asset loading" frameworks have refined it and made it pretty stable. common.js, require.js, etc have all done good jobs at this.
What should I know when I write the different components ?
For what you're doing with google maps, you don't really need to know much. but if you get into javascript module pattern development, you need to know this: make sure you protect your global namespace from being cluttered by your own variables, so encapsulate all of your work in closures when possible, and (recommended but not required) start them all with a ; so they don't break each other if they get loaded out of order.