angular.copy用法实例

        angular.copy(a,b)：将对象a深度拷贝至对象b，并返回对象b，完全拷贝所有数据，优点是b与a不会相互依赖（a,b完全脱离关联）。

        实例一：var r = angular.copy(a, b);将对象a中的属性深度拷贝给b对象，并返回b对象，即b、r引用的是同一个对象

var a = {
	name : 'bijian',
	address : 'shenzhen',
	family : {
		num : 6,
		amount : '80W'
	}
};
var b = {};
var r = angular.copy(a, b);
console.log('a:' + JSON.stringify(a));
console.log('b:' + JSON.stringify(b));
console.log('r:' + JSON.stringify(r));

b.address = 'hanzhou';
b.family.amount = '180W';
console.log('a:' + JSON.stringify(a));
console.log('b:' + JSON.stringify(b));
console.log('r:' + JSON.stringify(r));

运行结果：

a:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}}
b:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}}
r:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}}
a:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}}
b:{"name":"bijian","address":"hanzhou","family":{"num":6,"amount":"180W"}}
r:{"name":"bijian","address":"hanzhou","family":{"num":6,"amount":"180W"}}

 

        实例二：var r = angular.copy(a, b);将对象a中的属性深度拷贝给b对象,b与a不会相互依赖（a,b完全脱离关联）

var a = {
	name : 'bijian',
	address : 'shenzhen',
	family : {
		num : 6,
		amount : '80W'
	}
};
var b = {};
var r = angular.copy(a, b);
console.log('a:' + JSON.stringify(a));
console.log('b:' + JSON.stringify(b));
console.log('r:' + JSON.stringify(r));

a.address = 'hanzhou';
a.family.amount = '180W';
console.log('a:' + JSON.stringify(a));
console.log('b:' + JSON.stringify(b));
console.log('r:' + JSON.stringify(r));

运行结果：

a:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}}
b:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}}
r:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}}
a:{"name":"bijian","address":"hanzhou","family":{"num":6,"amount":"180W"}}
b:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}}
r:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}}

 

        实例三：var r = angular.copy(a);将对象a对象的属性深度拷贝给对象r

var a = {
	name : 'bijian',
	address : 'shenzhen',
	family : {
		num : 6,
		amount : '80W'
	}
};
var r = angular.copy(a);
console.log('a:' + JSON.stringify(a));
console.log('r:' + JSON.stringify(r));

a.address = 'hanzhou';
a.family.amount = '180W';
console.log('a:' + JSON.stringify(a));
console.log('r:' + JSON.stringify(r));

运行结果：

a:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}}
r:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}}
a:{"name":"bijian","address":"hanzhou","family":{"num":6,"amount":"180W"}}
r:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}}

 

        其实所有实例不如看源代码了解来的正确和直接，angular.copy源代码如下所示：

/**
 * @ngdoc function
 * @name angular.copy
 * @function
 *
 * @description
 * Creates a deep copy of `source`, which should be an object or an array.
 *
 * * If no destination is supplied, a copy of the object or array is created.
 * * If a destination is provided, all of its elements (for array) or properties (for objects)
 *   are deleted and then all elements/properties from the source are copied to it.
 * * If  `source` is not an object or array, `source` is returned.
 *
 * Note: this function is used to augment the Object type in Angular expressions. See
 * {@link ng.$filter} for more information about Angular arrays.
 *
 * @param {*} source The source that will be used to make a copy.
 *                   Can be any type, including primitives, `null`, and `undefined`.
 * @param {(Object|Array)=} destination Destination into which the source is copied. If
 *     provided, must be of the same type as `source`.
 * @returns {*} The copy or updated `destination`, if `destination` was specified.
 */
function copy(source, destination){
  if (isWindow(source) || isScope(source)) {
    throw ngMinErr('cpws', "Can't copy! Making copies of Window or Scope instances is not supported.");
  }

  if (!destination) {
    destination = source;
    if (source) {
      if (isArray(source)) {
        destination = copy(source, []);
      } else if (isDate(source)) {
        destination = new Date(source.getTime());
      } else if (isRegExp(source)) {
        destination = new RegExp(source.source);
      } else if (isObject(source)) {
        destination = copy(source, {});
      }
    }
  } else {
    if (source === destination) throw ngMinErr('cpi', "Can't copy! Source and destination are identical.");
    if (isArray(source)) {
      destination.length = 0;
      for ( var i = 0; i < source.length; i++) {
        destination.push(copy(source[i]));
      }
    } else {
      var h = destination.$$hashKey;
      forEach(destination, function(value, key){
        delete destination[key];
      });
      for ( var key in source) {
        destination[key] = copy(source[key]);
      }
      setHashKey(destination,h);
    }
  }
  return destination;
}