Passing Information from Twig to JavaScript
In Symfony applications, you may find that you need to pass some dynamic data
(e.g. user information) from Twig to your JavaScript code. One great way to pass
dynamic configuration is by storing information in data-*
attributes and reading
them later in JavaScript. For example:
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<div class="js-user-rating"
data-is-authenticated="{{ app.user ? 'true' : 'false' }}"
data-user="{{ app.user|serialize(format = 'json') }}"
>
<!-- ... -->
</div>
Fetch this in JavaScript:
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document.addEventListener('DOMContentLoaded', function() {
const userRating = document.querySelector('.js-user-rating');
const isAuthenticated = userRating.getAttribute('data-is-authenticated');
const user = JSON.parse(userRating.getAttribute('data-user'));
});
Note
If you prefer to access data attributes via JavaScript's dataset property,
the attribute names are converted from dash-style to camelCase. For example,
data-number-of-reviews
becomes dataset.numberOfReviews
:
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// ...
const isAuthenticated = userRating.dataset.isAuthenticated;
const user = JSON.parse(userRating.dataset.user);
There is no size limit for the value of the data-*
attributes, so you can
store any content. In Twig, use the html_attr
escaping strategy to avoid messing
with HTML attributes. For example, if your User
object has some getProfileData()
method that returns an array, you could do the following:
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<div data-user-profile="{{ app.user ? app.user.profileData|json_encode|e('html_attr') }}">
<!-- ... -->
</div>