insomnia/plugins/insomnia-plugin-jsonpath/index.js

const { JSONPath } = require('jsonpath-plus');

module.exports.templateTags = [
  {
    displayName: 'JSONPath',
    name: 'jsonpath',
    description: 'pull data from JSON strings with JSONPath',
    args: [
      {
        displayName: 'JSON string',
        type: 'string',
      },
      {
        displayName: 'JSONPath Filter',
        encoding: 'base64', // So it doesn't cause syntax errors
        type: 'string',
      },
    ],
    run(context, jsonString, filter) {
      let body;
      try {
        body = JSON.parse(jsonString);
      } catch (err) {
        throw new Error(`Invalid JSON: ${err.message}`);
      }

      let results;
      try {
        results = JSONPath({ json: body, path: filter });
      } catch (err) {
        throw new Error(`Invalid JSONPath query: ${filter}`);
      }

      if (results.length === 0) {
        throw new Error(`JSONPath query returned no results: ${filter}`);
      }

      return results[0];
    },
  },
];