how to use external javascript script for variables? - javascript

I have a very long script which included many variable definitions. I am using Openlayers.js to create a webmapping application which contains about 100 layers. Each layer has to be defined as a variable and bloats the script.
I thought I could simply create a layer.js file which contains the layer definitions and reference it before the main app.js in the html start page, but this is not working.
For reference,my javascript can be seen here: http://maps.zgb.de/geoportal/app.js
The first half-page is just defining variables.
Could anyone tell me what the best-practice is in this situation?
cheers

This might be of some help http://jacklmoore.com/notes/setcountdown/
They use images in that link but im sure the same would apply to pulling in script tags.
Alternatively you could have something like this
----- HTML Page -----
function loadApp() {
document.write('<script type="text/javascript" src="path/to/app.js"></script>');
}
---- Layers.js -----
var xyz = abc;
....
// right at the bpottom
loadApp();

Related

How to make JavaScript variables available to ES6 modules

Say I have a website with a file structure like this:
index.html
main.js
modules/my-module.js
index.html contains (along with a lot of HTML):
<button id='my-btn'>My Button</button>
<script type='module' src='./main.js'></script>
main.js contains:
import { myBtn } from "./modules/my-module.js";
and modules/my-module.js contains:
const myBtn = document.querySelector("#my-btn");
myBtn.addEventListener("click", function(){
alert("Hallo from My Button");
});
export { myBtn };
Now if I click on the button I get an alert as expected.
The problem I am having is that I have some information (ie variables with values such as strings, arrays etc) in other script tags on the index.html page which I need in modules/my-module.js
I do not want to use a global variable for this because they are evil.
I thought of creating an element(s) on the index.html page with data set attributes as keys and assign values to them. The element could then be accessed from modules/my-module.js and its data set attributes would be readable. This does work when I try it but it seems a long winded way of getting access to information available on the index.html page.
It has been suggested I create a class or function returned by the module and pass data into it. The problem with that, to me, is that I am trying to keep code related to the same thing all together in the same module. If I have to pass functions out of the module to be invoked with extra data then my code base is less well organised.
Is there any other approach which would be more direct?

How to place other JavaScript file links in a Javascript? [duplicate]

This question already has answers here:
How do I include a JavaScript file in another JavaScript file?
(70 answers)
Closed 6 years ago.
I have a bunch of JavaScript links at the bottom of one of my HTML template. I want to create a separate JavaScript file that will only contain all the source links in it.
So instead of cluttering my template footer I want all the links in one JavaScript file. How can I achieve that?
What I'm really asking is how I can get a similar effect as the CSS #import functionality for JavaScript.
And if that is not possible can I place a block of HTML at the footer of my template from a different HTML file?
You could do this with ajax but an easy way is to just append them with jquery
$('.div').append('<script src="myscript.js"></script>');
hope that helps
You can create a seperate js file and a object in it. This object can have multiple keys and their value will these links. Return this object from the file
Hope this snippet will be useful
linkFile.js
var AllLinks = function(){
var _links ={};
_links.keyOne ="link1";
_links.keyTwo ="link2";
return {
links:_links
}
}
Also include this file using script tag
In other file you can retrieve this value as
AllLinks.links.keyOne & so on
Have an array that holds the link to your script files and then you have two options either to use $.getScript() to load each one Or by building an HTML out of it and appending it to your head or body tag. I prefer head tag to keep all the scripts and css files.
Your array of script files
var JsFiles = ["script1.js","script2.js","script3.js","script4.js"];
First approach using $.getScript()
JsFiles.each(function(i,v){
$.getScript(JsFiles[i], function( data, textStatus, jqxhr){
console.log( textStatus ); // Success
});
});
Disadvantage of the above approach is that the getScript makes a async calls to your script files that means if the script2.js is dependent on the script1.js (for example if script1.js is some plugin file which use initialize in script2.js) Then you will face issues.
To overcome you might have to then use Promises or write a callback on each getScript success function which will trigger next script load and so on..
If the order of the script loading is not important then above approach is good to go.
Second approach by building HTML
var scriptTags ="";
JsFiles.each(function(i,v){
scriptTags += "<script src='"+ JsFiles[i] +"'></script>";
});
$('head').append(scriptTags);
Good thing about this approach is that the script files will now load synchronously and you will not face the dependency problem. But make sure the independent files start from first and the dependent files come at last.

How can I call a concrete Coffeecript function from html

I have an app that uses HTML, and Coffeescript in the frontend. I recently made it possible to change the language thanks to i18next.
Now I have some buttons that change my window.userLang to the different languages, but the user has to refresh some elements of the app to see it translated.
My problem comes because I need the translations made without refreshing the HTML.
In the app, I use Craftyjs, so what I need to know is how can (if possible) from HTML file, call a function that it's defined in Craftyjs.
The function I want to call is: Crafty.scene("main").
Thanks all!
Create a global name space defined above where your scripts are included. Then in your javascript you can define the functions you need as fields on that namespace.
<script>
var MySweetWebApp = {};
</script>
<script src="..."></script>
... Inside JS file ....
MySweetWebApp.Crafty = { ... }
... From Anywhere ...
MySweetWebApp.Crafty.scene('main');

MVC and javascript new approach; Q: May I have problems in future with this approach?

I will explain my idea behind this:
I use python for google app engine + js + css
the main project will be stored under the src folder like this:
\src
\app <--- here goes all the python app for gae
\javascript <--- my non-packed javascript files
\static_files <--- static files for gae
now the javascript dir looks like this
\javascript
\frameworks <--- maybe jQuery && jQueryUI
\models <--- js files
\controllers <--- js files
\views <--- HTML files!
app.js <--- the main app for js
compile.py <--- this is the file I will talk more
About compile.py:
This file will have 2 methods one for the min and other for the development javascript file;
When is run will do:
Join all the files with "js" extension;
The app.js contains a variable named "views" and is an object, like a hash; Then the compiler copy the contents of each file with "html" extension located in the "/javascript/views/" dir using this rule;
example: if we have a view like this "/views/login.html" then the "views" js var will have a property named "login"; views['login'] = '...content...';
example2: "/views/admin/sexyBitcy.html" then view['admin.sexyBitcy'] = '...content...' or whatever exists in that html file..;
Then this big file will be saved into the "/src/static_files/core.js"; if is minified will be saved as "/src/static_files/core.min.js";
The javascript will use dependenccy injection, or sort of it. (:
I will explain how it will work then:
the index.html that is loaded when you come into the site loads the core.js and the jquery.js;
the core.js will create the layout of the page, as SEO is not important for the most of the pages;
the core.js uses the controllers-models-views to create the layout of course; the html for the layout is inside the var "views"; will be a heavy variable of course!
Some code:
mvcInjector = new MVCInjector;
mvcInjector.mapView(views['login'], 'login', LoginController);
parent = $('#jscontent');
jquery
view = mvcInjector.instanceView('login', parent); // <--- this will create the contents of the views['login'] in the parent node "parent = $('#jscontent');" then will instance the LoginController that will map the "SkinParts" (like in FLEX if you know); what does it mean map the "SkinParts"? - when the user will click on a button an handler for that action is defined in the controller; ex.:
// LoginController
this.init = function(){
// map skin parts
this.mapSkinPart('email', 'input[name]="email"');
this.mapSkinPart('submit', 'input[name]="submit"');
// link skin parts to handlers
this.getSkinPart('submit').click = this.login;
}
// handlers
this.login = function(event){
// connect to the db
// some problems here the get the value as the "this" keyword references to the this of the controller class, I will work it around soon
alert('open window button1' + this.getSkinPart('email').value());
}
If something is not clear just say something, I will be happy to explain;
So the question remains: is this scalable, manageable and fast enough for a big RIA application build with javascript+jquery and maybe with jqueryUI?
Thanks ;)
I like your idea quit a bit.
I would think about loading html pages by ajax, if they are big and there are many of them...
Have a look on angular project, I hope, it could help you a lot. It's a kind of JS framework, designed to work together with jQuery. Well suitable for test driven development.
It uses html as templates, you can simply create your own controllers, use dependency injector, etc... Feel free to ask any question on mailing list.
Then, I must recommend JsTestDriver - really cool test runner for JS (so you can easily run unit tests in many browsers, during development - let's say after save...)

Passing Querystring style parameters into Javascript file

Not sure if this is possible or even if I should do it, but I think it's quite interesting.
I have a javascript file which I'm referencing in a flat HTML page. I'd like to pass in a parameter or two via the path to the script. Like this;
<script src="/scripts/myJavascriptFile.js?config1=true" type="text/javascript"></script>
Not really sure if it can work but it would make my solution a little easier for others to take my script and implement (arguable).
Cheers,
Mike
I don't think that passing in variables via the src attribute is possible out of the box without some extra coding on your part (there is an article here if you are interested!). You could do the following though, which should provide the same functionality as you are looking for:
Define your "config" variables in a single script block on your HTML page:
<script type="text/javascript">
var config1 = true;
</script>
Reference your external JS file in a second script block:
<script src="/scripts/myJavascriptFile.js" type="text/javascript"></script>
Add this code to your external JS file to reference the "local" variable in your HTML:
var conf1 = window.config1;
if (conf1) {
// Do stuff
}
This is a variation on Matt's answer. I have a similar case where I need a jQuery file to use a value that is generated in the HTML (by Razor in this case). I write the value to a meta tag, generated as it is from the controller:
<meta name="sessionId" content="#ViewBag.SessionId">
and then read it in the jQuery file:
var sessionId = $("meta[name=sessionId]").attr("content");
It's not quite the same as passing it in by querystring, but useful if that information is considered "meta-information" of the HTML page.

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