Tag Archives: Javascript Template

For us, the largest benefit of Javascript templating is reduced size

There are quite a few Javascript templates. In my projects however, there are very few cases where I would prefer using any of them in place of regular HTML being pushed out from the server (running Ruby-on-Rails). The same can be said of the Ponzu conference system.

As far as I understand, the benefits of using Javascript templates are 1) reducing the load on the server (generating JSON is less load than generating full HTML), 2) speed if used in combination with a single page design.

The downside is the additional work that browsers have to do, which can be a problem on mobile where the devices are not as powerful as their desktop counterparts.

I’ve touched this subject before in these two posts [1](https://code.castle104.com/?p=289), [2](https://code.castle104.com/?p=291).

As discussed by David Heinemeier Hansson, the same benefits can be achieved without Javascript templates by using a PJAX/Turbolinks/Kamishibai like system that eliminates reloading Javascript and CSS on each page transition, and the use of aggressive caching on the server side to reduce the load of HTML generation.

There is a real case however, where I feel a strong need for a Javascript tempting language.

That is when I try to cache responses in browser side cache. The issue is that HTML is extremely verbose, and is a real killer in terms of storage consumption when you are working with repetitive content.

For example, the following is a “social box” that we use in Ponzu for the like button and a voting button. It takes about 2,000 bytes. Each social box is associated with a presentation so we have hundreds to thousands of social boxes for each conference. This can easily fill up the limited browser side cache.

<div class="" id="presentation_326_social_box"><div class='like_box'>
<div class='like' id='like_button_326'>
<span class='social_controls'>
<!-- To invalidate Like related paths, we need a like object -->
<a href="/likes?like%5Bpresentation_id%5D=326" class="button icon like" rel="nofollow">like</a>
<div class='prompt_message'>
(
To add to your schedule, please &quot;like&quot; it first.
)
</div>
</span>
<div class='social_stats'>
<img alt="Like" src="/assets/like-c3719a03fc7b33c23fda846c3ccfb175.png" title="いいね!を押すと、応援メッセージになります。またあなたのスケジュールに登録されます。" />
<a href="/presentations/326/likes?user=1">15 people</a>
liked this.
</div>
<div class='likes_list' id='likes_presentation_326'></div>
</div>

</div>
<div class='vote_box'>
<div class='like' id='vote_button_326'>
<span class='social_controls'>
<form accept-charset="UTF-8" action="/likes/vote" class="new_like" id="presentation_326_new_like" method="post"><div style="margin:0;padding:0"></div>


<span>

<label for="presentation_326_like_score_1">Excellent!</label>
</span>
<span>

<label for="presentation_326_like_score_2">Unique!</label>
</span>
<span>

<label for="presentation_326_like_score_0">No Vote</label>
</span>
</form>
</span>
</div>

</div>
</div><div id="session_details_presentation_326"></div>

Most of this content is repetitive and will be identical for each “social_box”. In fact, the content that is unique to each individual social box can be summarized in the following JSON.

[{ 
    presentation_id:326,
    user_id:1,
    score: 0,
    liked: 0,
    scheduled: 0
}]

If we could use Javascript templating to generate the 2,000 byte HTML from this small set of JSON, local storage savings would be huge.

This is one feature that we will be adding to Kamishibai and Ponzu in the near future, to enable the ultimate goal of complete offline viewing.