Source contract and expected records
This is an original, fully synthetic mapping example. Inputs are plain, acyclic JSON-shaped records with the fields shown; the canonical shape and rejection codes belong to this example. Adapt the contract before using a different source.
Each locale row has a nonempty locale and text, with no duplicate locale. Require en and zh-HK, mapping them to en and zhHK fields. Keep other locale rows in unmapped. The function copies text; it cannot establish whether the two labels mean the same thing.
| Case | Input record (JSON) | Expected output (JSON) |
|---|---|---|
| Pair supplied locale text | {"entries":[{"locale":"en","text":"Front"},{"locale":"zh-HK","text":"前台"}]} | {"ok":true,"value":{"en":"Front","zhHK":"前台","unmapped":[]}} |
| Reject duplicate locale | {"entries":[{"locale":"en","text":"Front"},{"locale":"en","text":"Desk"},{"locale":"zh-HK","text":"前台"}]} | {"ok":false,"error":"LOCALE_DUPLICATE"} |
| Preserve another locale | {"entries":[{"locale":"en","text":"Front"},{"locale":"zh-HK","text":"前台"},{"locale":"fr","text":"Bureau"}]} | {"ok":true,"value":{"en":"Front","zhHK":"前台","unmapped":[{"locale":"fr","text":"Bureau"}]}} |
Run the local transformation
Run the complete example as a JavaScript module in Node.js. It contains the pure mapping function, all three inputs and literal expected outputs; assertions stop on a mismatch. A rejected case returns ok=false with an error code, rather than a partial canonical record.
import assert from 'node:assert/strict';
function localisedLabels(i){
const fail=error=>({ok:false,error});if(!i||!Array.isArray(i.entries))return fail('LOCALE_ENTRIES');
const found=new Map(),unmapped=[];
for(const e of i.entries){
if(!e||typeof e.locale!=='string'||!e.locale||typeof e.text!=='string'||!e.text)return fail('LOCALE_VALUE');
if(found.has(e.locale))return fail('LOCALE_DUPLICATE');found.set(e.locale,e.text);
if(!['en','zh-HK'].includes(e.locale))unmapped.push({locale:e.locale,text:e.text});
}
if(!found.has('en')||!found.has('zh-HK'))return fail('LOCALE_MISSING');
return {ok:true,value:{en:found.get('en'),zhHK:found.get('zh-HK'),unmapped}};
}
// Original synthetic cases; expected outputs are literal records.
const cases = [
{
"label": "Pair supplied locale text",
"input": {
"entries": [
{
"locale": "en",
"text": "Front"
},
{
"locale": "zh-HK",
"text": "前台"
}
]
},
"expected": {
"ok": true,
"value": {
"en": "Front",
"zhHK": "前台",
"unmapped": []
}
}
},
{
"label": "Reject duplicate locale",
"input": {
"entries": [
{
"locale": "en",
"text": "Front"
},
{
"locale": "en",
"text": "Desk"
},
{
"locale": "zh-HK",
"text": "前台"
}
]
},
"expected": {
"ok": false,
"error": "LOCALE_DUPLICATE"
}
},
{
"label": "Preserve another locale",
"input": {
"entries": [
{
"locale": "en",
"text": "Front"
},
{
"locale": "zh-HK",
"text": "前台"
},
{
"locale": "fr",
"text": "Bureau"
}
]
},
"expected": {
"ok": true,
"value": {
"en": "Front",
"zhHK": "前台",
"unmapped": [
{
"locale": "fr",
"text": "Bureau"
}
]
}
}
}
];
for (const sample of cases) {
const actual = localisedLabels(sample.input);
assert.deepEqual(actual, sample.expected);
console.log(sample.label, JSON.stringify(actual));
}
Work through the boundary
What happens to the French Bureau label in the preservation case?
Show the worked answer
It remains {locale:"fr",text:"Bureau"} in unmapped, beside Front and 前台. It is neither overwritten nor substituted for the required zh-HK row.