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Apply a string transformation recursively to all keys in a JSON-compatible object.

It's easiest to just show how this works.

Installation (get it from npm)

npm install recursive-json-key-transform


 * ES6/ES2015 syntax
import recursiveJSONKeyTransform from 'recursive-json-key-transform';
const convertAllKeysFromPascalCaseToCamelCase = (
  recursiveJSONKeyTransform((str) => {
    return str[0].toLowerCase() + str.slice(1);
const data = { Data1: { FieldA: 1, FieldB: false },
               Data2: [ { FieldC: "hello" } ] };
const camelCaseData = convertAllKeysFromPascalCaseToCamelCase(data);
 * prints:
 * { data1: { fieldA: 1, fieldB: false },
 *   data2: [ { fieldC: 'hello' } ] }

recursiveJSONKeyTransform accepts one argument, a transformer function that accepts a string and returns a string. The result of recursiveJSONKeyTransform(transformerFn) is another function, which accepts a JSON-compatible JavaScript object. It returns a deep copy of that object with all object keys transformed according to the specified transformer function (including objects nested inside of arrays).

Any object will work, but if it contains JSON-incompatible properties (e.g. functions), they will be ignored (or interpreted as empty objects). The module's intended use is for JSON responses from APIs, which may contain object keys in a format different than your application's convention.