| 1 | ## Javascript
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| 3 | Smartdown is intended to serve a broad audience, enabling the teaching and explanation of many different subjects. Some of these subjects such as **Computer Science** and **Programming** and **Linguistics** demand the ability to express, share, explain and execute code. Smartdown embraces this idea by making it easy to *play* code fragments of various forms into the document.
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| 5 | Currently, only Javascript is supported within Smartdown, although it is trivial to build upon this to support per-document embedded languages.
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| 7 | This Javascript integration will evolve to be safer and more convenient. Currently, Smartdown variables are *strings*, and must be converted. The *reactivity* in Smartdown is currently not as good as it could be, so an explicit call to `smartdown.setVariable()` is required to trigger other cells and playables to update.
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| 9 | In the same way that Smartdown accommodates a diversity of *playable* languages, including GraphViz, Mermaid, and other DSLs (Domain-specific Languages), it can and eventually will include a diversity of executable languages via a *playable plugin mechanism*. Right now, though, Javascript is the primary *scripting* language for Smartdown.
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| 11 | ---
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| 13 | This example is totally useless. Every time you *play* the script, it increments a Smartdown variable named `COUNTER`.
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| 15 | [Counter](:!COUNTER)
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| 18 | ```javascript/playable
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| 19 | var counter = env.COUNTER || 0;
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| 20 | ++counter;
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| 21 | smartdown.setVariable('COUNTER', counter, 'integer');
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| 22 | ```
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| 24 | ---
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| 26 | [Back to Home](:@Home)
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