json8-patch/lib/add.js

JSON Patch toolkit for JavaScript

"use strict";

const ooPointer = require("json8-pointer");
const decode = ooPointer.decode;
const walk = require("./walk");

/**
 * @typedef OperationResult
 * @type Object
 * @property {Any}   doc       - The patched document
 * @property {Array} previous  - The previous/replaced value if any
 */

/**
 * Add the value to the specified JSON Pointer location
 * http://tools.ietf.org/html/rfc6902#section-4.1
 *
 * @param  {Any}  doc    - JSON document to set the value to
 * @param  {Path} path   - JSON Pointer string or tokens path
 * @param  {Any}  value  - value to add
 * @return {OperationResult}
 */
module.exports = function add(doc, path, value) {
  const tokens = decode(path);

  // replaces the document
  if (tokens.length === 0) return { doc: value, previous: doc };

  const r = walk(doc, tokens);
  const token = r[0];
  const parent = r[1];

  let previous;
  let idx;

  if (Array.isArray(parent)) {
    if (token === "-") {
      parent.push(value);
      idx = parent.length - 1;
    } else parent.splice(token, 0, value);
  } else {
    previous = parent[token];
    parent[token] = value;
  }

  return { doc: doc, previous: previous, idx: idx };
};