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

const jq = require('jsonpath');

module.exports.templateTags = [{
  displayName: 'JSONPath',
  name: 'jsonpath',
  description: 'Pull data from JSON strings with JSONPath',
  args: [{
    displayName: 'JSON string',
    type: 'string'
  }, {
    displayName: 'JSONPath Filter',
    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 = jq.query(body, 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];
  }
}];