I'm trying to make a variable (eventually to be replaced by more complex json selected from the database) accessible to client-side javascript. I wanted to load it when the page is rendered instead of an ajax call and its not going to be rendered via a template like ejs (I want to pass the data to an extjs store for a combobox). So I have a standart response I render:
function (req, res) {
res.render('index.html', {foo: ['a','b']});
}
and a blank html page I want to access foo:
<!DOCTYPE html>
<html>
<head>
<script type=text/javascript>
console.log(foo);
</script>
</head>
<body>
</body>
</html>
any ideas? I've thought of maybe writing the whole html page via res.send() (which has a few more things than the example above) but that seems like such a workaround for something that should be obvious to do...
Assuming the same array foo in your question above, here are a couple ways you could do this.
This one uses an EJS filter to write an array literal:
<script type="text/javascript">
var foo = ['<%=: foo | join:"', '" %>'];
</script>
This one encodes it as JSON, to later be parsed by your client-side javascript:
<script type="text/javascript">
// note the "-" instead of "=" on the opening tag; it avoids escaping HTML entities
var fooJSON = '<%-JSON.stringify(foo)%>';
</script>
IIRC, ExtJS can handle JSON directly as its data. If not, then you could use its JSON parser first and then hand it a local variable. If you weren't using ExtJS, you could use this to parse on the client: https://github.com/douglascrockford/JSON-js
If you choose to encode it as JSON, it would make it also make it easier to later switch back to AJAX for retrieving your data. In some cases, that would have an advantage. The page could load and display some data, along with a busy icon over the element for which you're loading data.
This isn't to say there's anything inherently wrong with including all the data in the original request. It's just that sticking with JSON gives you the flexibility to choose later.
In EJS the following should work
<script type=text/javascript>
console.log( <%= foo %>);
</script>
I do recommend against dynamically generating JavaScript though as it breaks seperation of concerns and forces JavaScript to be on.
Edit:
Turns out the above doesn't work nicely for arrays. So simply encode your data in semantic HTML. Then enhance it with JavaScript. If the JavaScript must get data then store it somewhere more sensible like the cookie or retrieve it through ajax.
Related
I understand that this a bit odd of a question but here I go. I am writing an application that will be switching environments (dev, test, prod, etc). I need the base URL for my REST calls to change as I switch environments. Well, our current solution (and I am all ears for better solutions) is a local REST call asking the server what environment I am in and what URL I should be using for my base. The external REST calls are separated from the front end completely.
With the local REST call I could do an ajax call to get the data somewhere in my javascript or I could include the REST call as follows:
<script src="/rest/configs"></script>
The problem with the above solution is that it returns an object that is not assigned to a variable thus throwing errors. So my over all question is, Can you load a REST call through a script tag straight into a variable and if so, how?
If you do this with a script tag the response of the request ( not AJAX at all ) will be parsed and executed as javascript.
What you could do is to return valid Javascript, rather than JSON object. Something like
window.config = {"env":"test"};
rather than
{"env":"test"}
Other option is not to do this with script tag and just write inline javascript with an ajax call. If you use jQuery it would look like :
<script>$.get("/rest/configs", function(config) { window.config = config; });</script>
This will do the Ajax call and assign it to a global variable config. Of course you should make some adjustments and execute the rest of your javascript after this is executed.
Anyway as a standard, this value is usually hard-coded in the scripts. I would suggest to create a script that is modified for test/dev/production environments.
Can't your rest call just return a Javascript object, like so:
var env = "experimental";
Your webpage should be able to interpret this as Javascript and the env variable should be usable in the rest of your page:
<html>
<head>
<script type="text/javascript" src="/rest/configs"></script>
<script type="text/javascript">
console.log("env: " + env); // prints env: experimental
</script>
</head>
<body></body>
</html>
I have a url [https://www.inquicker.com/facility/americas-family-doctors.json] that is a JSON data url. How can I access the contents of this url, and write out the values.
The format contains schedules as an array that inside it contains schedule_id, name, and available_times. I have tried various ways of getting the JSON file, but none have worked.
UPDATE:
Well I have got it this far with this code, and it's laying out what looks like objects from the array. So I believe I got the cross site issue under control. I just need to figure out how to access the data now.
<!DOCTYPE html>
<html>
<head>
<title>JQuery (cross-domain) JSONP</title>
<script type="text/javascript"src="http://ajax.googleapis.com/ajax/libs/jquery/1.7/jquery.min.js"> </script>
<script>
$(document).ready(function(){
$.getJSON('https://www.inquicker.com/facility/americas-family-doctors.json',
function(data){
alert(data.facility);
$.each(data.schedules, function(i, name){
$('#names').append('<li>' + name.available_times[0] + '</li>');
});
});
});
</script>
</head>
<body>
<ul id="names"></ul>
</body>
</html>
Any help, or suggestions will be greatly appreciated, Thanks.
You cannot generally pass an Ajax request across domains. Normally a server will refuse any Ajax calls that don't come from the same source unless it is explicitly configured otherwise. I am guessing that you aren't calling from the same domain, given that you are using a fully-qualified URL. If you own the server, you will have to configure it to accept such calls from your other domain.
If this is not the case, launch the script in Firefox with Firebug running and look at the console output and tell me what error you get if any.
Once you manage to pass the JSON from your server back to the page, you will retrieve it in your JavaScript as a string. You then need to execute this function:
var jsonObject = JSON.parse(jsonString);
where jsonString is the string that you received from your server. jsonObject becomes an object representation of the JSON passed back to the answer that you can access using dot notation.
Try something like :
alert(json.facility);
There is no title json object in the url you have mentioned.
The JSON is already parsed when it comes to your function.
$.get('https://www.inquicker.com/facility/americas-family-doctors.json', function(result){
alert(result.facility); //Do whatever you want here
// result.schedules array is also ready
});
I have an update panel with a timer control set up to automatically check for some data updates every minute or so.
If it sees that the data updates, it is set to call a local script with the serialized JSON data.
ScriptManager.RegisterStartupScript(UpdateField, GetType(HiddenField), ACTION_CheckHistoryVersion, "updateData(" & data & ");", True)
where "data" might look something like
{
"someProperty":"foo",
"someOtherProperty":"bar",
"someList":[
{"prop1":"value"},
{"prop2":"value"}, ...
],
"someOtherList":[{},...,{}]
}
"data" can get quite large, and sometimes only a few items change.
The problem I am having is this. Every time I send this back to the client, it gets added as a brand new script block and the existing blocks do not get removed or replaced.
output looks something like this:
<script type="text/javascript">
updateData({
"someProperty":"foo",
"someOtherProperty":"bar",
"someList":[
{"prop1":"value"},
{"prop2":"value"}, ...
],
"someOtherList":[{},...,{}]
});
</script>
<script type="text/javascript">
updateData({
"someProperty":"foo",
"someOtherProperty":"bar",
"someList":[
{"prop1":"changed"},
{"prop2":"val"}, ...
],
"someOtherList":[{},...,{}]
});
</script>
<script type="text/javascript">
updateData({
"someProperty":"foos",
"someOtherProperty":"ball",
"someList":[
{"prop1":"changed"},
{"prop2":"val"}, ...
]
});
</script>
with a new script block being created every time there is a change in the data.
Over time the amount of data accumulating on the browser could get potentially huge if we just keep adding this and I can't imagine how most people's browser would take it, but I don't think it could be good.
Does anyone know if there is a way to just replace the code that has been sent back to the browser rather than continuously adding it like this?
I came up with a hack that seems to work in my situation.
I am using jQuery to find the script tag that I am creating and remove it after it has been called.
Here is an example:
First I generate a guid:
Dim guidText as string = GUID.NewGuid().ToString()
I create a function like the following:
function RemoveThisScript(guid){
$("script").each(function(){
var _this = $(this);
if(_this.html().indexOf(guid)>-1)
_this.remove();
});
}
Then I add the following code to my output string:
... & " RemoveThisScript('" & guidText & "');"
This causes jQuery to look through all the scripts on the page for one that has the GUID (essentially the one calling the function) and removes it from the DOM.
I would recommend to use web service with some webmethod which you will call inside window.setInterval. In success handler of your webmethod (on client side) you can just take response and do whatever you want with it. And it will not be saved in your page (well, if you will do everything wrong). Benefit is that you will minimize request size(updatepanel will pass all your viewstate data, which could be large enough) and will limit server resources usage (update panel is causing full page live cycle, suppose slightly modified, but anyway - all those page_load, page_init, etc...) and with web service you will only what you need.
Here is an article where you can see how it could be created and used on client side. Looks like good enough.
I am completely lost on this; I am using NodeJS to fetch a JSON and I need to pass the variable to my page and have JavaScript use the data.
app.get('/test', function(req, res) {
res.render('testPage', {
myVar: 'My Data'
});
That is my Express code (very simple for testing purposes); now using JADE I want to gather this data which I know to render on the page is simply
p= myVar
But I need to be able to gather this data in JavaScript (if possible within a .js file) but for now just to display the variable in an Alert box I have tried
alert(#{myVar})
And many others if anyone can help be much appreciated
Try the following:
alert('!{myVar}')
It's a good idea to JSON encode the data if is more than just a string.
alert('!{JSON.stringify(myVar)}')
As Timothy said:
<script type="text/javascript"> var myVar = #{JSON.stringify(myVar)}; </script>
This can also be done as follows in if you don't like to write HTML in Jade/Pug templates:
script
var myVar = !{JSON.stringify(myVar)};
var myVar2 = !{JSON.stringify(myVar2)};
Update: For Express 4 and Pug use script. instead of script so that it will be rendered as javascript instead of html.
Well, Javascript (and V8) has a built in function to render JSON from a object, and JSON happens to be syntactially compatible with Javascript.
So the easiest way to do what your trying to do would be:
<script type="text/javascript>var myVar = #{JSON.stringify(myVar)};</script>
And, yes, you can use HTML in a Jade template.
I know I'm a bit late to the party, but I actually wrote a module (JShare) a few months ago to solve this exact problem. Check it out: https://npmjs.org/package/jshare
You could leverage Now.js for this. It easily allows you to share variables client/server side real-time.
Check it out: http://www.nowjs.com/
I'm using restclient and nokogiri to parse some html which works great, but there is one piece of information stored in a js (jquery) variable which I need to return and I'm not sure how to parse it. I can use Nokogiri to parse the javascript block, but I need one subset of it which is probably simple but I'm not sure how to do it. I could probably regex it but I'm assuming there's an easier way to just ask for it using JS.
#resource = RestClient.get 'http://example.com'
doc = Nokogiri::HTML(#resource)
doc.css('script').each do |script|
puts script.content
end
What I'm trying to get:
<script type="text/javascript">
$(function(){
//this is it
$.Somenamespace.theCurrency = 'EUR';
//a lot more stuff
not sure if that fits, but you could retrieve it as follows:
irb(main):017:0>
string
=> "<script type=\"text/javascript\"> $(function(){$.Somenamespace.theCurrency = \"EUR\"}); "
irb(main):018:0>
string.scan(/\$\.Somenamespace\.(.*)}\);/)
=> [["theCurrency = \"EUR\""]]
Nokogiri is an XML and HTML parser. It doesn't parse the CDATA or text content of nodes, but it can give you the content, letting you use string parsing or regex to get at the data you want.
In the case of Javascript, if it's embedded in the page then you can get the text of the parent node. Often that is simple:
js = doc.at('script').text
if there is the usual <script> tag in the <head> block of the page. If there are multiple script tags you have to extend the accessor to retrieve the right node, then process away.
It gets more exciting when the scripts are loaded dynamically, but you can still get the data by parsing the URL from the script's src parameter, then retrieving it, and processing away again.
Sometimes Javascript is embedded in the links of other tags, but it's just another spin on the previous two methods to get the script and process it.