deepmerge2/index.js

A library for deep (recursive) merging of Javascript objects

(function(root, factory) {
  if(typeof define === 'function' && define.amd) {
    define(factory);
  } else if(typeof exports === 'object') {
    module.exports = factory();
  } else {
    root.deepmerge = factory();
  }
}(this, function() {
  function deepmerge(target, src) {
    var array = Array.isArray(src);
    var dst = array && [] || {};

    if(array) {
      target = target || [];
      dst = dst.concat(target);
      src.forEach(function(e, i) {
        if(typeof dst[i] === 'undefined') {
          dst[i] = e;
        } else if(typeof e === 'object' && e !== null) {
          dst[i] = deepmerge(target[i], e);
        } else {
          if(target.indexOf(e) === -1) {
            dst.push(e);
          }
        }
      });
    } else {
      if(target && typeof target === 'object') {
        Object.keys(target).forEach(function(key) {
          dst[key] = target[key];
        })
      }
      Object.keys(src).forEach(function(key) {
        switch(true) {
          case typeof src[key] !== 'object':
          case !src[key]:
          case src[key] instanceof Date:
          case src[key] instanceof RegExp: {
            dst[key] = src[key];
            break;
          }

          default: {
            if(!target[key]) {
              dst[key] = src[key];
            } else {
              dst[key] = deepmerge(target[key], src[key]);
            }
          }
        }
      });
    }

    return dst;
  }

  return function deepMergeWrapper(target) {
    var result = target;

    Array.prototype.slice.call(arguments, 1).forEach(function(elem) {
      result = deepmerge(result, elem);
    });

    return result;
  }
}));