How to pass variable from jade template file to a script file?

#{} is for escaped string interpolation which automatically escapes the input and is thus more suitable for plain strings rather than JS objects:

script var data = #{JSON.stringify(data)}

<script>var data = {&quot;foo&quot;:&quot;bar&quot;} </script>

!{} is for unescaped code interpolation, which is more suitable for objects:

script var data = !{JSON.stringify(data)}

<script>var data = {"foo":"bar"} </script>

CAUTION: Unescaped code can be dangerous. You must be sure to sanitize any user inputs to avoid cross-site scripting (XSS).

E.g.:

{ foo: 'bar </script><script> alert("xss") //' }

will become:

<script>var data = {"foo":"bar </script><script> alert("xss") //"}</script>

Possible solution: Use .replace(/<\//g, '<\\/')

script var data = !{JSON.stringify(data).replace(/<\//g, '<\\/')}

<script>var data = {"foo":"bar<\/script><script>alert(\"xss\")//"}</script>

The idea is to prevent the attacker to:

1. Break out of the variable: JSON.stringify escapes the quotes
2. Break out of the script tag: if the variable contents (which you might not be able to control if comes from the database for ex.) has a </script> string, the replace statement will take care of it

https://github.com/pugjs/pug/blob/355d3dae/examples/dynamicscript.pug

In my case, I was attempting to pass an object into a template via an express route (akin to OPs setup). Then I wanted to pass that object into a function I was calling via a script tag in a pug template. Though lagginreflex's answer got me close, I ended up with the following:

script.
    var data = JSON.parse('!{JSON.stringify(routeObj)}');
    funcName(data)

This ensured the object was passed in as expected, rather than needing to deserialise in the function. Also, the other answers seemed to work fine with primitives, but when arrays etc. were passed along with the object they were parsed as string values.

If you're like me and you use this method of passing variables a lot, here's a write-less-code solution.

In your node.js route, pass the variables in an object called window, like this:

router.get('/', function (req, res, next) {
    res.render('index', {
        window: {
            instance: instance
        }
    });
});

Then in your pug/jade layout file (just before the block content), you get them out like this:

if window
    each object, key in window
        script.
            window.!{key} = !{JSON.stringify(object)};

As my layout.pug file gets loaded with each pug file, I don't need to 'import' my variables over and over.

This way all variables/objects passed to window 'magically' end up in the real window object of your browser where you can use them in Reactjs, Angular, ... or vanilla javascript.

See this question: JADE + EXPRESS: Iterating over object in inline JS code (client-side)?

I'm having the same problem. Jade does not pass local variables in (or do any templating at all) to javascript scripts, it simply passes the entire block in as literal text. If you use the local variables 'address' and 'port' in your Jade file above the script tag they should show up.

Possible solutions are listed in the question I linked to above, but you can either: - pass every line in as unescaped text (!= at the beginning of every line), and simply put "-" before every line of javascript that uses a local variable, or: - Pass variables in through a dom element and access through JQuery (ugly)

Is there no better way? It seems the creators of Jade do not want multiline javascript support, as shown by this thread in GitHub: https://github.com/visionmedia/jade/pull/405

Here's how I addressed this (using a MEAN derivative)

My variables:

{
  NODE_ENV : development,
  ...
  ui_varables {
     var1: one,
     var2: two
  }
}

First I had to make sure that the necessary config variables were being passed. MEAN uses the node nconf package, and by default is set up to limit which variables get passed from the environment. I had to remedy that:

config/config.js:

original:

nconf.argv()
  .env(['PORT', 'NODE_ENV', 'FORCE_DB_SYNC'] ) // Load only these environment variables
  .defaults({
  store: {
    NODE_ENV: 'development'
  }
});

after modifications:

nconf.argv()
  .env('__') // Load ALL environment variables
  // double-underscore replaces : as a way to denote hierarchy
  .defaults({
  store: {
    NODE_ENV: 'development'
  }
});

Now I can set my variables like this:

export ui_varables__var1=first-value
export ui_varables__var2=second-value

Note: I reset the "heirarchy indicator" to "__" (double underscore) because its default was ":", which makes variables more difficult to set from bash. See another post on this thread.

Now the jade part: Next the values need to be rendered, so that javascript can pick them up on the client side. A straightforward way to write these values to the index file. Because this is a one-page app (angular), this page is always loaded first. I think ideally this should be a javascript include file (just to keep things clean), but this is good for a demo.

app/controllers/index.js:

'use strict';
var config = require('../../config/config');

exports.render = function(req, res) {
  res.render('index', {
    user: req.user ? JSON.stringify(req.user) : "null",
    //new lines follow:
    config_defaults : {
       ui_defaults: JSON.stringify(config.configwriter_ui).replace(/<\//g, '<\\/')  //NOTE: the replace is xss prevention
    }
  });
};

app/views/index.jade:

extends layouts/default

block content
  section(ui-view)
    script(type="text/javascript").
    window.user = !{user};
    //new line here
    defaults = !{config_defaults.ui_defaults};

In my rendered html, this gives me a nice little script:

<script type="text/javascript">
 window.user = null;         
 defaults = {"var1":"first-value","var2:"second-value"};
</script>        

From this point it's easy for angular to utilize the code.