Twig Functions: add 'json_pp' filter

doc/TwigJS.md

@@ -78,6 +78,8 @@ Extra filters:
 * filter `debug`: print the value (and further arguments) to the javascript console (via `console.log()`)
 * filter `wikipediaAbstract`: shows the abstract of a Wikipedia article in the selected data language (or, if not available, the language which was used in input, resp. 'en' for Wikidata input). Input is either 'language:article' (e.g. 'en:Douglas Adams') or a wikidata id (e.g. 'Q42').
 * filter `wikidataEntity`: returns the wikidata entity in structured form (or `null` if the entity is not cached or `false` if it does not exist). Example: https://www.wikidata.org/wiki/Special:EntityData/Q42.json
+* filter `json_pp`: JSON pretty print the object. As parameter to the filter, the following options can be passed:
+  * `indent`: indentation (default: 2)
 
 Notes:
 * Variables will automatically be HTML escaped, unless the filter raw is used, e.g.: `{{ tags.name|raw }}`

src/twigFunctions.js

@@ -140,3 +140,11 @@ OverpassLayer.twig.extendFilter('debug', function (value, param) {
   console.log.apply(null, [ value, ...param ])
   return value
 })
+OverpassLayer.twig.extendFilter('json_pp', function (value, param) {
+  const options = param[0] || {}
+
+  value = JSON.parse(JSON.stringify(value))
+  delete value._keys // remove TwigJS artefact
+
+  return JSON.stringify(value, null, 'indent' in options ? ' '.repeat(options.indent) : '  ')
+})