Add format items filter to core filters

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### New features
 
+- [#2384: Add format items filter to core filters](https://github.com/alphagov/govuk-prototype-kit/pull/2384)
 - [#2382: Make any npm module a plugin via a proxy plugin config](https://github.com/alphagov/govuk-prototype-kit/pull/2382)
 
 ## 13.15.3

lib/filters/core-filters.js

@@ -2,14 +2,51 @@
 const { runWhenEnvIsAvailable, external } = require('./api')
 const { addFilter, getFilter } = external
 
-/**
- * Logs an object in the template to the console in the browser.
- * @param  {Any} a any type
- * @return {String} a script tag with a console.log call.
- * @example {{ "hello world" | log }}
- * @example {{ "hello world" | log | safe }}  [for environments with autoescaping turned on]
- */
 runWhenEnvIsAvailable(() => {
   const nunjucksSafe = getFilter('safe')
-  addFilter('log', a => nunjucksSafe('<script>console.log(' + JSON.stringify(a, null, '\t') + ');</script>'))
+
+  addFilter(
+    'log',
+    /**
+     * Logs an object in the template to the console in the browser.
+     *
+     * @example
+     * ```njk
+     * {{ "hello world" | log }}
+     * ```
+     * @param {any} a - any type
+     * @returns {string} a script tag with a console.log call.
+     */
+    (a) => nunjucksSafe('<script>console.log(' + JSON.stringify(a, null, '\t') + ');</script>')
+  )
+
+  addFilter(
+    'formatItems',
+    /**
+     * Returns an array of objects for use in a macro that requires a list of items
+     *
+     * @example
+     * ```njk
+     * {{ govukCheckboxes({
+     *   name: "waste",
+     *   fieldset: {
+     *     legend: {
+     *       text: "Which types of waste do you transport?",
+     *       isPageHeading: true,
+     *       classes: "govuk-fieldset__legend--l"
+     *     }
+     *   },
+     *   hint: {
+     *     text: "Select all that apply."
+     *   },
+     *   items: ["Rubble", "Oil", "Card"] | formatItems
+     * }) }}
+     * ```
+     * @param  {string[]} items - an array of strings.
+     * @returns {{ text: string, value: string }[]} an array of objects with text and value properties.
+     */
+    (items = []) => Array.isArray(items)
+      ? items.map((item) => ({ text: item, value: item }))
+      : []
+  )
 })