Pass variables to JavaScript in ExpressJS

Question

Pass variables to JavaScript in ExpressJS

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 EJS I want to gather this data which I know to render on the page is simply

<%= 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

In Jade it is like alert('!{myVar}') or !{JSON.stringify(myVar)}. Can I do something similar in EJS. I don't need any field like <input type=hidden> and taking the value of the field in javascript. If anyone can help be much appreciated

javascript
node.js
express
ejs

Answer 1

You could use this (client-side):

<script>
  var myVar = <%- JSON.stringify(myVar) %>;
</script>

You could also get EJS to render a .js file:

app.get('/test.js', function(req, res) {
  res.set('Content-Type', 'application/javascript');
  res.render('testPage', { myVar : ... });
});

However, the template file (testPage) would still need to have the .html extension, otherwise EJS won't find it (unless you tell Express otherwise).

Answer 2

Try this:

<script type="text/javascript">
     window.addEventListener('load', function(){
         alert('<%= myVar %>');
     });
</script>

Answer 3

Per the documentation here:

Go to the Latest Release, download ./ejs.js or ./ejs.min.js.

Include one of these on your page, and ejs.render(str).