js深拷贝

js深拷贝

export const $ = function() {
  var copyIsArray,
    toString = Object.prototype.toString,
    hasOwn = Object.prototype.hasOwnProperty,
    class2type = {
      '[object Boolean]': 'boolean',
      '[object Number]': 'number',
      '[object String]': 'string',
      '[object Function]': 'function',
      '[object Array]': 'array',
      '[object Date]': 'date',
      '[object RegExp]': 'regExp',
      '[object Object]': 'object'
    },
    type = function(obj) {
      return obj == null ? String(obj) : class2type[toString.call(obj)] || "object";
    },
    isWindow = function(obj) {
      return obj && typeof obj === "object" && "setInterval" in obj;
    },
    isArray = Array.isArray || function(obj) {
      return type(obj) === "array";
    },
    isPlainObject = function(obj) {
      if (!obj || type(obj) !== "object" || obj.nodeType || isWindow(obj)) {
        return false;
      }
      if (obj.constructor && !hasOwn.call(obj, "constructor") &&
        !hasOwn.call(obj.constructor.prototype, "isPrototypeOf")) {
        return false;
      }
      var key;
      for (key in obj) {}
      return key === undefined || hasOwn.call(obj, key);
    },
    extend = function(deep, target, options) {
      for (var name in options) {
        var src = target[name];
        var copy = options[name];
        if (target === copy) {
          continue;
        }
        if (deep && copy &&
          (isPlainObject(copy) || (copyIsArray = isArray(copy)))) {
          if (copyIsArray) {
            copyIsArray = false;
            var clone = src && isArray(src) ? src : [];
          } else {
            var clone = src && isPlainObject(src) ? src : {};
          }
          target[name] = extend(deep, clone, copy);
        } else if (copy !== undefined) {
          target[name] = copy;
        }
      }
      return target;
    };
  return { extend: extend };
}();