denest.js

/** @typedef {string|boolean|number|Function|void} nonObject */

/**
 * @typedef {[string, nonObject]} DenestedRow
 * @property {string} path     The dot/bracket notation of the variable. (Example: `a.b[0].c["d-e"].f`). Same as `this[0]`.
 * @property {object} parent   The object that holds this variable.
 * @property {string} key      The key to this variable. (`this.parent[this.key] === this[1]`)
 */

/**
 * Concatenates an object and nested objects into a single key-value array.
 * Useful for turning an object into a table.
 * @param  {object} object
 * @return {DenestedRow[]}
 */
export default function denest(object) {
  /** @type {DenestedRow[]} */
  const table = [];
  /** @type {string[]} */
  const path = [];
  /** @type {[object, string[], number][]} */
  const state = [[
    object,
    Object.keys(object),
    0
  ]];
  const goodKey = /^[a-zA-Z_][a-zA-Z0-9_]*$/;

  loop: do {
    const object = state[0][0];
    const length = state[0][1].length;
    for (let i = state[0][2]; i < length; i++) {
      const k = state[0][1][i];
      if (object[k] && typeof object[k] === 'object') {
        state[0][2] = i + 1;
        path.push(
          goodKey.test(k)
          ? (path.length > 0 ? '.' : '') + k
          : '['+ (isNaN(k) ? JSON.stringify(k) : k) +']'
        );
        state.unshift([
          object[k],
          Object.keys(object[k]),
          0
        ]);
        continue loop;
      } else {
        /** @type {DenestedRow} */
        const row = [
          path.concat(
            goodKey.test(k)
            ? (path.length > 0 ? '.' : '') + k
            : '['+ (isNaN(k) ? JSON.stringify(k) : k) +']'
          ).join(''),
          object[k]
        ];
        row.path = row[0];
        row.parent = object;
        row.key = k;
        table.push(row);
      }
    }
    path.pop();
    state.shift();
  } while (state.length > 0);

  return table;
}