I have some javascript code which requires few fields from server side. I would like to store this code in a separate .js file but, moustache will not be able to populate it with server side information. This is what I have:
<body>
<script type="text/javascript" src="/js/test.js"></script>
</body>
My .js file:
var testField = '{{someValue}}';
alert(testField); // is null
Thank you
You can try to use eval js function: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/eval
var testTemplate = '{{someValue}}';
var testTemplateValue = Mustache.render(testTemplate, view);
var testField = eval(testTemplateValue);
alert(testField);
Eval function is not secure, so you must take care about input manually.
For example, I have an script like this: <script src="myjs.js?lol=asd"></script>.
Is there anyway to get the lol inside the js file to alert it, for example, like we can do in PHP? Like:
var lol = $_GET['lol'];
alert(lol);
Use the code from How may I reference the script tag that loaded the currently-executing script? to get a reference to the script tag:
var scripts = document.getElementsByTagName('script');
var thisScriptTag = scripts[scripts.length - 1];
Then you can use thisScriptTag.src to access its src attribute and parse it to get the variable you are looking for
You can't do this with javascript.
I want to include a script tag, while providing a parameter to it. This is what I came up with so far
Provide a parameter to script URL (cons: generate multiple JS files)
<script src="http://example.com/something.js?P=123" type="text/javascript"></script>
Hide parameter in script tag (cons: same as #1)
<script src="http://example.com/scripts/123/something.js" type="text/javascript"></script>
Google Analytics way (cons: ugly, complicated, global variables)
<script type="text/javascript" charset="utf-8">
var _something = _something || 123;
(function() {
var s = document.createElement('script');
s.type = 'text/javascript';
s.src = 'http://example.com/something.js';
var ss = document.getElementsByTagName('script')[0];
ss.parentNode.insertBefore(s, ss);
})();
</script>
The best thing is to define things (functions &c) in the external script but execute nothing. Then have an inline script that calls functions/methods defined in the external script.
<script src="http://example.com/something.js" type="text/javascript"></script>
<script type="text/javascript">
something(123);
</script>
If the way the script is executed, depends on how it's called, you can add params like your option 1.
Other ways are:
<script params='{"abc": 123}' src="script.js"></script><!-- params is a non standard, non official attr that the script will read -->
or
<script>var _abc = 123;</script>
<script src="script.js"></script>
or even
<script src="script.js#abc=123"></script>
I have to agree with #outis though: load the same thing for everybody, always, and execute it like you/the client want(s) afterwards.
I do this for a cross-sub-domain XHR handler that I have. I call it as:
<script type="text/javascript" src="xd.js#subdomain"></script>
and then in the script, parse it as such (using jQuery):
$('script').each(function(){
if((src = this.src).indexOf('xd.js') < 0){ return; }
xds = src.substr(src.indexOf('#') + 1).split(',');
// do stuff with xds
});
Your first example does not need to generate multiple files. It can be used by JavaScript alone, by detecting window.location.href and parsing it (you might find the likes of http://phpjs.org/functions/parse_url:485 and http://phpjs.org/functions/parse_str:484 helpful in doing this: var queryString = parse_str(parse_url(window.location.href).query); ).
However, if you use something like #P=123 instead of ?P=123, you won't cause another download of the file by your users, so I'd recommend that instead (in which case change "query" in the above code sample to "fragment").
Another possibility is using the HTML5-reserved data-* attributes, and detecting their values within your script:
<script src="http://example.com/something.js" data-myOwnAttribute="someValue" data-anotherCustomAttribute="anotherValue"></script>
The script would then detect along these lines:
(function () {
function getScriptParam (attr) {
var scripts = document.getElementsByTagName('script'),
currentScript = scripts[scripts.length-1];
return currentScript.getAttribute('data-' + attr); // in future, could just use the HTML5 standard dataset attribute instead: currentScript.dataset[attr]
}
var myOwnAttribute = getScriptParam('myOwnAttribute');
// ... do stuff here ...
}());
The real advantage of Google's ugly API is that it allows developers to drop in that code in the <head> of the document (considered proper form), while still acting asynchronously in a cross-browser way. I think they could indeed avoid the global had they combined their dynamic script-tag technique with either of the above approaches.
I have a following Kohana setup:
All my files are placed under 'public_html/koh'
My js files are placed under 'public_html/koh/media/js/'
I use html::script helper to include those javascript files which generates me following html code:
<script type="text/javascript" src="/koh/media/js/site.js"></script>
In my js I access one of controllers like 'json/getsomething' (which is http://localhost/koh/json/getsomething).
It works OK as long as I'm staying in top of the controller:
http://localhost/koh/home
When I go to 'http://localhost/koh/home/index' it renders the same page of course but 'json/getsomething' is not accessible from Javascript anymore.
How can I solve this problem?
Include Javascript using absolute path?
Create a variable in js like var fullPath = 'http://localhost/koh/'?
What is the best practice to do it?
Leonti
That's how I did it.
I made a function url_base which would correspond to kohana's url::base and so it would switch around when I moved from localhost and to production.
View template:
<script type="text/javascript">
function url_base() { return "<?php echo url::base();?>"; }
</script>
And then in config.php:
if(IN_PRODUCTION) {
$config['site_domain'] = '/';
}
else {
//if in localhost redirect to localhost/mysite
//instead of just localhost
$config['site_domain'] = '/mysite/';
}
(A bit late but hope still useful) Here's another way I use to better organize my js-serverside vars.
I put somewhere in beginning some basic variables - eg. in "before()" function:
$this->template->appconf = array(
'url_base' => url::base(),
'l' => substr(I18n::$lang, 0, 2),
);
Now I can add whenever I need any extra variable:
$this->template->appconf['page_key'] = 'product_page';
And finally in template this cleaniness:
<script type="text/javascript">
var appconf = <?php echo json_encode($appconf); ?>;
</script>
Use like this:
<script type="text/javascript">
console.log(appconf.url_base); // "/mysite/"
</script>
Often I will have a JavaScript file that I want to use which requires certain variables be defined in my web page.
So the code is something like this:
<script type="text/javascript" src="file.js"></script>
<script type="text/javascript">
var obj1 = "somevalue";
</script>
But what I want to do is:
<script type="text/javascript"
src="file.js?obj1=somevalue&obj2=someothervalue"></script>
I tried different methods and the best one yet is to parse the query string like this:
var scriptSrc = document.getElementById("myscript").src.toLowerCase();
And then search for my values.
I wonder if there is another way to do this without building a function to parse my string.
Do you all know other methods?
I'd recommend not using global variables if possible. Use a namespace and OOP to pass your arguments through to an object.
This code belongs in file.js:
var MYLIBRARY = MYLIBRARY || (function(){
var _args = {}; // private
return {
init : function(Args) {
_args = Args;
// some other initialising
},
helloWorld : function() {
alert('Hello World! -' + _args[0]);
}
};
}());
And in your html file:
<script type="text/javascript" src="file.js"></script>
<script type="text/javascript">
MYLIBRARY.init(["somevalue", 1, "controlId"]);
MYLIBRARY.helloWorld();
</script>
You can pass parameters with arbitrary attributes. This works in all recent browsers.
<script type="text/javascript" data-my_var_1="some_val_1" data-my_var_2="some_val_2" src="/js/somefile.js"></script>
Inside somefile.js you can get passed variables values this way:
........
var this_js_script = $('script[src*=somefile]'); // or better regexp to get the file name..
var my_var_1 = this_js_script.attr('data-my_var_1');
if (typeof my_var_1 === "undefined" ) {
var my_var_1 = 'some_default_value';
}
alert(my_var_1); // to view the variable value
var my_var_2 = this_js_script.attr('data-my_var_2');
if (typeof my_var_2 === "undefined" ) {
var my_var_2 = 'some_default_value';
}
alert(my_var_2); // to view the variable value
...etc...
Another idea I came across was assigning an id to the <script> element and passing the arguments as data-* attributes. The resulting <script> tag would look something like this:
<script id="helper" data-name="helper" src="helper.js"></script>
The script could then use the id to programmatically locate itself and parse the arguments. Given the previous <script> tag, the name could be retrieved like this:
var name = document.getElementById("helper").getAttribute("data-name");
We get name = helper
Check out this URL. It is working perfectly for the requirement.
http://feather.elektrum.org/book/src.html
Thanks a lot to the author. For quick reference I pasted the main logic below:
var scripts = document.getElementsByTagName('script');
var myScript = scripts[ scripts.length - 1 ];
var queryString = myScript.src.replace(/^[^\?]+\??/,'');
var params = parseQuery( queryString );
function parseQuery ( query ) {
var Params = new Object ();
if ( ! query ) return Params; // return empty object
var Pairs = query.split(/[;&]/);
for ( var i = 0; i < Pairs.length; i++ ) {
var KeyVal = Pairs[i].split('=');
if ( ! KeyVal || KeyVal.length != 2 ) continue;
var key = unescape( KeyVal[0] );
var val = unescape( KeyVal[1] );
val = val.replace(/\+/g, ' ');
Params[key] = val;
}
return Params;
}
You use Global variables :-D.
Like this:
<script type="text/javascript">
var obj1 = "somevalue";
var obj2 = "someothervalue";
</script>
<script type="text/javascript" src="file.js"></script">
The JavaScript code in 'file.js' can access to obj1 and obj2 without problem.
EDIT Just want to add that if 'file.js' wants to check if obj1 and obj2 have even been declared you can use the following function.
function IsDefined($Name) {
return (window[$Name] != undefined);
}
Hope this helps.
Here is a very rushed proof of concept.
I'm sure there are at least 2 places where there can be improvements, and I'm also sure that this would not survive long in the wild. Any feedback to make it more presentable or usable is welcome.
The key is setting an id for your script element. The only catch is that this means you can only call the script once since it looks for that ID to pull the query string. This could be fixed if, instead, the script loops through all query elements to see if any of them point to it, and if so, uses the last instance of such an script element. Anyway, on with the code:
Script being called:
window.onload = function() {
//Notice that both possible parameters are pre-defined.
//Which is probably not required if using proper object notation
//in query string, or if variable-variables are possible in js.
var header;
var text;
//script gets the src attribute based on ID of page's script element:
var requestURL = document.getElementById("myScript").getAttribute("src");
//next use substring() to get querystring part of src
var queryString = requestURL.substring(requestURL.indexOf("?") + 1, requestURL.length);
//Next split the querystring into array
var params = queryString.split("&");
//Next loop through params
for(var i = 0; i < params.length; i++){
var name = params[i].substring(0,params[i].indexOf("="));
var value = params[i].substring(params[i].indexOf("=") + 1, params[i].length);
//Test if value is a number. If not, wrap value with quotes:
if(isNaN(parseInt(value))) {
params[i] = params[i].replace(value, "'" + value + "'");
}
// Finally, use eval to set values of pre-defined variables:
eval(params[i]);
}
//Output to test that it worked:
document.getElementById("docTitle").innerHTML = header;
document.getElementById("docText").innerHTML = text;
};
Script called via following page:
<script id="myScript" type="text/javascript"
src="test.js?header=Test Page&text=This Works"></script>
<h1 id="docTitle"></h1>
<p id="docText"></p>
might be very simple
for example
<script src="js/myscript.js?id=123"></script>
<script>
var queryString = $("script[src*='js/myscript.js']").attr('src').split('?')[1];
</script>
You can then convert query string into json like below
var json = $.parseJSON('{"'
+ queryString.replace(/&/g, '","').replace(/=/g, '":"')
+ '"}');
and then can use like
console.log(json.id);
This can be easily done if you are using some Javascript framework like jQuery.
Like so,
var x = $('script:first').attr('src'); //Fetch the source in the first script tag
var params = x.split('?')[1]; //Get the params
Now you can use these params by splitting as your variable parameters.
The same process can be done without any framework but will take some more lines of code.
Well, you could have the javascript file being built by any of the scripting languages, injecting your variables into the file on every request. You would have to tell your webserver to not dish out js-files statically (using mod_rewrite would suffice).
Be aware though that you lose any caching of these js-files as they are altered constantly.
Bye.
HTML:
<script src='greet.js' data-param1='hello' data-param2='world'></script>
// greet.js:
const prm1=document.currentScript.dataset.param1;
const prm2=document.currentScript.dataset.param2;
Nice question and creative answers but my suggetion is to make your methods paramterized and that should solve all your problems without any tricks.
if you have function:
function A()
{
var val = external_value_from_query_string_or_global_param;
}
you can change this to:
function B(function_param)
{
var val = function_param;
}
I think this is most natural approach, you don't need to crate extra documentation about 'file parameters' and you receive the same. This specially useful if you allow other developers to use your js file.
It's not valid html (I don't think) but it seems to work if you create a custom attribute for the script tag in your webpage:
<script id="myScript" myCustomAttribute="some value" ....>
Then access the custom attribute in the javascript:
var myVar = document.getElementById( "myScript" ).getAttribute( "myCustomAttribute" );
Not sure if this is better or worse than parsing the script source string.
Here i have found an another way of doing this same thing. In the reuired js file [cttricks.js as i have used it for testing, you can have your any .js file], we'll simply list up all script elements and get the required one as it is always going to be at last index. And then get ".attributes.src.value" from that.
Now, in any case of script call, it is
<script src="./cttricks.js?data1=Hello&data2=World"></script>
And in the cttricks.js script file,
var scripts = document.getElementsByTagName('script');
var jsFile = new URL("http://" + scripts[scripts.length-1].attributes.src.value);
/*get value from query parameters*/
console.log(jsFile.searchParams.get("data1"));
console.log(jsFile.searchParams.get("data2"));
Enjoy!!
No, you cant really do this by adding variables to the querystring portion of the JS file URL. If its writing the portion of code to parse the string that bothers you, perhaps another way would be to json encode your variables and put them in something like the rel attribute of the tag? I don't know how valid this is in terms of HTML validation, if thats something you're very worried about. Then you just need to find the rel attribute of the script and then json_decode that.
eg
<script type='text/javascript' src='file.js' rel='{"myvar":"somevalue","anothervar":"anothervalue"}'></script>
If you need a way that passes CSP check (which prohibits unsafe-inline) then you have to use nonce method to add a unique value to both the script and the CSP directive or write your values into the html and read them again.
Nonce method for express.js:
const uuidv4 = require('uuid/v4')
app.use(function (req, res, next) {
res.locals.nonce = uuidv4()
next()
})
app.use(csp({
directives: {
scriptSrc: [
"'self'",
(req, res) => `'nonce-${res.locals.nonce}'` // 'nonce-614d9122-d5b0-4760-aecf-3a5d17cf0ac9'
]
}
}))
app.use(function (req, res) {
res.end(`<script nonce="${res.locals.nonce}">alert(1 + 1);</script>`)
})
or write values to html method. in this case using Jquery:
<div id="account" data-email="{{user.email}}"></div>
...
$(document).ready(() => {
globalThis.EMAIL = $('#account').data('email');
}
Although this question has been asked a while ago, it is still relevant as of today. This is not a trivial approach using script file params, but I already had some extreme use-cases that this way was most suited.
I came across this post to find out a better solution than I wrote a while ago, with hope to find maybe a native feature or something similar.
I will share my solution, up until a better one will be implemented. This works on most modern browsers, maybe even on older ones, didn't try.
All the solutions above, are based on the fact that it has to be injected with predefined and well marked SCRIPT tag and rely completely on the HTML implementation. But, what if the script is injected dynamically, or even worse, what if you are write a library, that will be used in a variety of websites?
In these and some other cases, all the above answers are not sufficient and even becoming too complicated.
First, let's try to understand what do we need to achieve here. All we need to do is to get the URL of the script itself, from there it's a piece of cake.
There is actually a nice trick to get the script URL from the script itself. One of the functionalities of the native Error class, is the ability to provide a stack trace of the "problematic location", including the exact file trace to the last call. In order to achieve this, I will use the stack property of the Error instance, that once created, will give the full stack trace.
Here is how the magic works:
// The pattern to split each row in the stack trace string
const STACK_TRACE_SPLIT_PATTERN = /(?:Error)?\n(?:\s*at\s+)?/;
// For browsers, like Chrome, IE, Edge and more.
const STACK_TRACE_ROW_PATTERN1 = /^.+?\s\((.+?):\d+:\d+\)$/;
// For browsers, like Firefox, Safari, some variants of Chrome and maybe other browsers.
const STACK_TRACE_ROW_PATTERN2 = /^(?:.*?#)?(.*?):\d+(?::\d+)?$/;
const getFileParams = () => {
const stack = new Error().stack;
const row = stack.split(STACK_TRACE_SPLIT_PATTERN, 2)[1];
const [, url] = row.match(STACK_TRACE_ROW_PATTERN1) || row.match(STACK_TRACE_ROW_PATTERN2) || [];
if (!url) {
console.warn("Something went wrong. You should debug it and find out why.");
return;
}
try {
const urlObj = new URL(url);
return urlObj.searchParams; // This feature doesn't exists in IE, in this case you should use urlObj.search and handle the query parsing by yourself.
} catch (e) {
console.warn(`The URL '${url}' is not valid.`);
}
}
Now, in any case of script call, like in the OP case:
<script type="text/javascript" src="file.js?obj1=somevalue&obj2=someothervalue"></script>
In the file.js script, you can now do:
const params = getFileParams();
console.log(params.get('obj2'));
// Prints: someothervalue
This will also work with RequireJS and other dynamically injected file scripts.
I think it is far more better and modern solution to just use localStorage on the page where the javascript is included and then just re-use it inside the javascript itself. Set it in localStorage with:
localStorage.setItem("nameOfVariable", "some text value");
and refer to it inside javascript file like:
localStorage.getItem("nameOfVariable");
It's possible to pass parameters to js modules and read them after via import.meta.url.
For example, with the following HTML
<script type="module">
import './index.mjs?someURLInfo=5';
</script>
the following JavaScript file will log the someURLInfo parameter:
// index.mjs
new URL(import.meta.url).searchParams.get('someURLInfo'); // 5
The same applies when a file imports another:
// index.mjs
import './index2.mjs?someURLInfo=5';
// index2.mjs
new URL(import.meta.url).searchParams.get('someURLInfo'); // 5