I’m working with a Handlebars template file (.hbs) where I can display data using syntax like {{username}}. This works fine for displaying values directly in the HTML.
Now I need to use these Handlebars variables inside JavaScript code within a <script> tag in the same template file. Basic JavaScript like alert(5); runs without issues, but I can’t figure out how to access the Handlebars variables from within the script.
I tried this approach but it doesn’t work:
{{username}}
<script type="text/javascript">
var template = Handlebars.compile('{{username}}');
var userName = template({});
$.getJSON("http://localhost:3000/users/" + userName + "/summary.json", function(data) {
num = data.topics[0].id;
});
</script>
How can I properly use the Handlebars variable in my JavaScript code? I want to display the num variable in the template next to {{username}}.
You’re attempting to use a Handlebars variable within a <script> tag in your Handlebars template, but the variable isn’t being passed correctly to your JavaScript code. Your current approach involves trying to re-compile the Handlebars template within the JavaScript, which is unnecessary and incorrect because the Handlebars template is already processed server-side.
Understanding the “Why” (The Root Cause):
Handlebars templates are typically pre-processed on the server. This means that before the HTML is sent to the client’s browser, Handlebars replaces the placeholder variables (like {{username}}) with their actual values. Therefore, when your browser receives and executes the JavaScript code within the <script> tag, the Handlebars variables have already been replaced, and there’s no need to re-compile them client-side. Attempting to use Handlebars.compile within the client-side JavaScript in this context is incorrect.
Step-by-Step Guide:
Step 1: Directly Output the Variable to Your JavaScript. Instead of trying to re-compile the Handlebars template within JavaScript, output the value of your Handlebars variable directly into your JavaScript code. The server-side rendering will have already substituted the variable with its correct value.
<script type="text/javascript">
var userName = "{{username}}"; // The server already rendered this value
$.getJSON("http://localhost:3000/users/" + userName + "/summary.json", function(data) {
var num = data.topics[0].id;
// Update the DOM to display 'num'
document.getElementById('numDisplay').innerHTML = num;
});
</script>
<span id="numDisplay"></span> <!-- Add this span to your HTML -->
Step 2: Add a Placeholder Element to Your HTML. Add a <span> element (or any other suitable HTML element) with a unique ID (numDisplay in this example) to your HTML. This element will serve as the container where the num variable’s value will be displayed.
Step 3: Update the DOM. Within your AJAX success callback function, use document.getElementById('numDisplay').innerHTML = num; to dynamically update the content of the placeholder element with the value of the num variable retrieved from your API call.
Common Pitfalls & What to Check Next:
Escaping Special Characters: If your username variable contains special characters (like quotes or HTML tags), ensure that they are properly escaped on the server-side before being embedded in the JavaScript code to prevent XSS vulnerabilities. Server-side escaping within the Handlebars template is the best approach.
API Endpoint: Double-check the correctness of your API endpoint: "http://localhost:3000/users/" + userName + "/summary.json". Ensure that the base URL and the path are accurate and that your server is running correctly.
Error Handling: Add error handling to your AJAX call to gracefully handle potential network errors or situations where the API response doesn’t contain the expected data.topics[0].id. A simple error callback function in the $.getJSON call is recommended.
Template Structure: Ensure your Handlebars template is correctly structured and that the {{username}} variable is available in the data context passed to the template engine.
Still running into issues? Share your (sanitized) config files, the exact command you ran, and any other relevant details. The community is here to help!
Just pass the data straight to JavaScript. Use JSON.stringify to handle strings and objects properly.
<script type="text/javascript">
var userName = {{{json username}}}; // triple braces for unescaped output
// or if you don't have a json helper:
var userName = "{{{username}}}";
$.getJSON("http://localhost:3000/users/" + userName + "/summary.json", function(data) {
var num = data.topics[0].id;
// now you can use num in your template
$("#someElement").text(num);
});
</script>
Honestly though, mixing server templating with client API calls gets messy fast. I ran into this exact problem last year and ended up automating everything.
Instead of juggling Handlebars variables and AJAX calls, I built a workflow that fetches user data, processes it, and updates the frontend automatically. No more template headaches.
The automation handles API calls, data transformation, and UI updates in one flow. Way cleaner than mixing templating languages with JavaScript.
Everyone’s suggesting manual fixes, but just automate this. I had the exact same problem building user dashboards with real-time updates.
Yeah, you can inject variables like var userName = '{{username}}'; but you’ll hit escaping issues with special characters. And you’re still stuck with that messy template + AJAX pattern.
I automated it instead. Built a flow that pulls user data from the API, processes it, and pushes updates straight to the frontend. No more mixing Handlebars with JavaScript or template headaches.
The workflow handles data fetching, variable passing, and DOM updates automatically. User data changes? Everything updates in real time without touching templates.
Way cleaner than fighting server-side templating and client-side scripts. You can build the same thing at https://latenode.com
You’re mixing client-side and server-side compilation. Your template gets processed server-side before hitting the browser, so Handlebars.compile() won’t work there.
I hit this exact problem building a dashboard last month. Cleanest fix is using a data attribute:
<div id="userContainer" data-username="{{username}}"></div>
<script type="text/javascript">
var userName = document.getElementById('userContainer').getAttribute('data-username');
$.getJSON("http://localhost:3000/users/" + userName + "/summary.json", function(data) {
var num = data.topics[0].id;
document.getElementById('userContainer').innerHTML = "User: {{username}}, Topics: " + num;
});
</script>
This keeps your data separate from JavaScript logic and dodges XSS issues with direct variable injection. Data attributes are way more maintainable when you’ve got multiple variables to pass around.
Understanding the “Why” (The Root Cause):
Step-by-Step Guide:
Common Pitfalls & What to Check Next:
Still running into issues? Share your (sanitized) config files, the exact command you ran, and any other relevant details. The community is here to help!