diff-obj/lib/diff.js

'use strict';

const is = require('is');
const extend = require('extend');

function diff(from, to, options) {
  if (!is.object(from) || !is.object(to)) {
    throw new Error('参数 from 或 to 未定义');
  }

  // 当 options 不存在，则给她个初始对象
  if (!options) {
    options = {
      added: {},
      removed: {},
      changed: {},
      unchanged: {},
      prefix: null,
    };
  }

  const {added, removed, changed, unchanged, prefix} = options;

  for (let key in from) {
    let value1 = from[key];
    let value2 = to[key];

    const value = {
      from: value1,
      to: value2,
    };

    // 如果两个值都是数组，则需要转为 JSON 进行比较
    if (is.array(value1) && is.array(value2)) {
      value1 = JSON.stringify(value1);
      value2 = JSON.stringify(value2);
    }

    if (value1 === value2) {
      unchange(key, value, options);
    } else if (is.defined(value1) && is.undef(value2)) {
      remove(key, value, options);
    } else if (is.object(value1) && is.object(value2)) {
      diff(value1, value2, extend({}, options, {
        prefix: join(prefix, key),
      }));
    } else {
      change(key, value, options);
    }
  }

  for (let key in to) {
    const value1 = from[key];
    const value2 = to[key];

    const value = {
      from: value1,
      to: value2,
    };

    if (is.undef(value1) && is.defined(value2)) {
      add(key, value, options);
    }
  }

  return {
    added,
    removed,
    changed,
    unchanged,
  };
}

function join(key1, key2) {
  if (!key1) {
    return key2;
  }
  return [key1, key2].join('.');
}

function add(key, value, options) {
  const {added, prefix} = options;
  added[join(prefix, key)] = value;
}

function remove(key, value, options) {
  const {removed, prefix} = options;
  removed[join(prefix, key)] = value;
}

function change(key, value, options) {
  const {changed, prefix} = options;
  changed[join(prefix, key)] = value;
}

function unchange(key, value, options) {
  const {unchanged, prefix} = options;
  unchanged[join(prefix, key)] = value;
}

module.exports = diff;