angular.extend用法实例-白红宇

angular.extend用法实例

阅读量：6897 次

发布时间：2019-06-27

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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bvar 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：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bvar 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);//这里其实不关 a.family什么事，因为被后续的z给覆盖了 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';//这里改变不了a.familyconsole.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":{
    "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：/** * @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; }