Add Spanish as a UI language

README.md

@@ -41,7 +41,7 @@ load and the matching results at each moment.
 The **?** icon next to each calculator's title explains the theory: how it works, the key design
 insights and the assumptions behind the formulas (hover on desktop, tap on touch screens).
 
-The site is available in **English, German, Dutch and Turkish**. Pick a language in the header; the
+The site is available in **English, German, Spanish, Dutch and Turkish**. Pick a language in the header; the
 choice is remembered in the browser. It covers the whole interface, calculator labels and results,
 warnings, sketches, the theory notes and the PDF report.
 
@@ -89,7 +89,7 @@ optionally a sketch to `js/preview.js`, and a check to `tests/run-tests.js`.
 
 ## Translations
 
-English is the source language. Texts are written in English in the code, and `js/i18n/de.js`,
+English is the source language. Texts are written in English in the code, and `js/i18n/de.js`, `es.js`,
 `nl.js` and `tr.js` map each English text to its translation (`PEC.t(text, vars)` looks it up and
 falls back to English). `npm test` lists any text that has no translation, so when you add or change
 a label, warning, theory note or sketch text, add the same English key to each language file.

index.html

@@ -62,6 +62,7 @@ <h3 id="libTitle" data-i18n="Saved calculations">Saved calculations</h3>
   <script src="js/core.js"></script>
   <script src="js/i18n.js"></script>
   <script src="js/i18n/de.js"></script>
+  <script src="js/i18n/es.js"></script>
   <script src="js/i18n/nl.js"></script>
   <script src="js/i18n/tr.js"></script>
   <script src="js/materials.js"></script>

js/i18n.js

@@ -11,6 +11,7 @@
   var LANGS = [
     { code: 'en', name: 'English', locale: 'en-GB' },
     { code: 'de', name: 'Deutsch', locale: 'de-DE' },
+    { code: 'es', name: 'Español', locale: 'es-ES' },
     { code: 'nl', name: 'Nederlands', locale: 'nl-NL' },
     { code: 'tr', name: 'Türkçe', locale: 'tr-TR' }
   ];