AngularJS extend用法详解及实例代码

2019-11-19 18:58:17

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AngularJS extend用法

angular.extend:依次将第二个参数及后续的参数的第一层属性（不管是简单属性还是对象）拷贝赋给第一个参数的第一层属性，即如果是对象，则是引用的是同一个对象，并返回第一个参数对象。

实例一：var r = angular.extend(b, a);将对象a的第一层属性（不管是简单属性还是对象）拷贝赋给对象b的第一层属性，即如果是对象，则是引用的是同一个对象，并返回对象b

Js代码

var a = {   name : 'bijian',   address : 'shenzhen',   family : {     num : 6,     amount : '80W'   } }; var b = {}; var r = angular.extend(b, a); 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：

Text代码

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":"180W"}} 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.extend(b, a, z);相继将对象a、z的第一层属性（不管是简单属性还是对象）拷贝赋给对象b的第一层属性，即如果是对象，则是引用的是同一个对象，并返回对象b

Js代码

var a = {   name : 'bijian',   address : 'shenzhen',   family : {     num : 6,     amount : '80W'   } }; var z = {   family : {     amount : '150W',     mainSource : '经营公司'   } }; var b = {}; var r = angular.extend(b, a, z); 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：

Text代码

a:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}} b:{"name":"bijian","address":"shenzhen","family":{"amount":"150W","mainSource":"经营公司"}} r:{"name":"bijian","address":"shenzhen","family":{"amount":"150W","mainSource":"经营公司"}} a:{"name":"bijian","address":"shenzhen","family":{"num":6,"amount":"80W"}} b:{"name":"bijian","address":"hanzhou","family":{"amount":"180W","mainSource":"经营公司"}} r:{"name":"bijian","address":"hanzhou","family":{"amount":"180W","mainSource":"经营公司"}}

再多的实例也不如源代码来的简单、直接和准确，angular.extend源码如下：

Js代码

/**  * @ngdoc function  * @name angular.extend  * @function  *  * @description  * Extends the destination object `dst` by copying all of the properties from the `src` object(s)  * to `dst`. You can specify multiple `src` objects.  *  * @param {Object} dst Destination object.  * @param {...Object} src Source object(s).  * @returns {Object} Reference to `dst`.  */ function extend(dst) {  var h = dst.$$hashKey;  forEach(arguments, function(obj){   if (obj !== dst) {    forEach(obj, function(value, key){     dst[key] = value;    });   }  });   setHashKey(dst,h);  return dst; }

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