我需要能够在运行时合并两个(非常简单)JavaScript对象。例如,我想:
var obj1 = { food: 'pizza', car: 'ford' }
var obj2 = { animal: 'dog' }
obj1.merge(obj2);
//obj1 now has three properties: food, car, and animal
是否有一种内置的方法来实现这一点?我不需要递归,也不需要合并函数,只需要平面对象上的方法。
我需要能够在运行时合并两个(非常简单)JavaScript对象。例如,我想:
var obj1 = { food: 'pizza', car: 'ford' }
var obj2 = { animal: 'dog' }
obj1.merge(obj2);
//obj1 now has three properties: food, car, and animal
是否有一种内置的方法来实现这一点?我不需要递归,也不需要合并函数,只需要平面对象上的方法。
当前回答
与jQueryextend()类似,AngularJS中有相同的函数:
// Merge the 'options' object into the 'settings' object
var settings = {validate: false, limit: 5, name: "foo"};
var options = {validate: true, name: "bar"};
angular.extend(settings, options);
其他回答
这是我的刺
支持深度合并不改变参数采用任意数量的参数不扩展对象原型不依赖于其他库(jQuery、MooTools、Undercore.js等)包括检查hasOwnProperty短:)/*递归合并财产并返回新对象对象1<;-对象2[<;-…]*/函数合并(){变量dst={},srcp,args=[].splice.call(参数,0);while(参数长度>0){src=参数拼接(0,1)[0];if(toString.call(src)=='[object object]'){for(src中的p){if(src.hasOwnProperty(p)){if(toString.call(src[p])=='[object object]'){dst[p]=合并(dst[p]||{},src[p]);}其他{dst[p]=src[p];}}}}}返回dst;}
例子:
a = {
"p1": "p1a",
"p2": [
"a",
"b",
"c"
],
"p3": true,
"p5": null,
"p6": {
"p61": "p61a",
"p62": "p62a",
"p63": [
"aa",
"bb",
"cc"
],
"p64": {
"p641": "p641a"
}
}
};
b = {
"p1": "p1b",
"p2": [
"d",
"e",
"f"
],
"p3": false,
"p4": true,
"p6": {
"p61": "p61b",
"p64": {
"p642": "p642b"
}
}
};
c = {
"p1": "p1c",
"p3": null,
"p6": {
"p62": "p62c",
"p64": {
"p643": "p641c"
}
}
};
d = merge(a, b, c);
/*
d = {
"p1": "p1c",
"p2": [
"d",
"e",
"f"
],
"p3": null,
"p5": null,
"p6": {
"p61": "p61b",
"p62": "p62c",
"p63": [
"aa",
"bb",
"cc"
],
"p64": {
"p641": "p641a",
"p642": "p642b",
"p643": "p641c"
}
},
"p4": true
};
*/
顺便说一句,你们正在做的是覆盖财产,而不是合并。。。
这就是JavaScript对象区域真正合并的方式:只有to对象中不是对象本身的键才会被from覆盖。其他一切都将被真正合并。当然,您可以将此行为更改为不覆盖任何存在的内容,例如仅当to[n]未定义时,等等…:
var realMerge = function (to, from) {
for (n in from) {
if (typeof to[n] != 'object') {
to[n] = from[n];
} else if (typeof from[n] == 'object') {
to[n] = realMerge(to[n], from[n]);
}
}
return to;
};
用法:
var merged = realMerge(obj1, obj2);
ECMAScript 2018标准方法
您可以使用对象扩散:
let merged = {...obj1, ...obj2};
merged现在是obj1和obj2的并集。obj2中的财产将覆盖obj1中的属性。
/** There's no limit to the number of objects you can merge.
* Later properties overwrite earlier properties with the same name. */
const allRules = {...obj1, ...obj2, ...obj3};
这里还有此语法的MDN文档。如果您正在使用babel,则需要@babel/plugin提议对象rest spread插件才能工作(该插件包含在ES2018中的@babel/preset-env中)。
ECMAScript 2015(ES6)标准方法
/* For the case in question, you would do: */
Object.assign(obj1, obj2);
/** There's no limit to the number of objects you can merge.
* All objects get merged into the first object.
* Only the object in the first argument is mutated and returned.
* Later properties overwrite earlier properties with the same name. */
const allRules = Object.assign({}, obj1, obj2, obj3, etc);
(参见MDN JavaScript参考)
ES5及更早版本的方法
for (var attrname in obj2) { obj1[attrname] = obj2[attrname]; }
请注意,这将简单地将obj2的所有属性添加到obj1中,如果您仍然希望使用未修改的obj1,那么这可能不是您想要的。
如果你使用的是一个在你的原型上到处都是垃圾的框架,那么你必须通过hasOwnProperty这样的检查来获得更高的效率,但这段代码在99%的情况下都是有效的。
示例函数:
/**
* Overwrites obj1's values with obj2's and adds obj2's if non existent in obj1
* @param obj1
* @param obj2
* @returns obj3 a new object based on obj1 and obj2
*/
function merge_options(obj1,obj2){
var obj3 = {};
for (var attrname in obj1) { obj3[attrname] = obj1[attrname]; }
for (var attrname in obj2) { obj3[attrname] = obj2[attrname]; }
return obj3;
}
jQuery还有一个实用程序:http://api.jquery.com/jQuery.extend/.
摘自jQuery文档:
// Merge options object into settings object
var settings = { validate: false, limit: 5, name: "foo" };
var options = { validate: true, name: "bar" };
jQuery.extend(settings, options);
// Now the content of settings object is the following:
// { validate: true, limit: 5, name: "bar" }
上面的代码将改变现有的名为setting的对象。
如果要在不修改任何参数的情况下创建新对象,请使用以下命令:
var defaults = { validate: false, limit: 5, name: "foo" };
var options = { validate: true, name: "bar" };
/* Merge defaults and options, without modifying defaults */
var settings = $.extend({}, defaults, options);
// The content of settings variable is now the following:
// {validate: true, limit: 5, name: "bar"}
// The 'defaults' and 'options' variables remained the same.
我使用Object.create()来保持默认设置(使用__proto__或Object.getPrototypeOf())。
function myPlugin( settings ){
var defaults = {
"keyName": [ "string 1", "string 2" ]
}
var options = Object.create( defaults );
for (var key in settings) { options[key] = settings[key]; }
}
myPlugin( { "keyName": ["string 3", "string 4" ] } );
这样我以后就可以一直使用“concat()”或“push()”。
var newArray = options['keyName'].concat( options.__proto__['keyName'] );
注意:为了避免重复,需要在连接之前进行hasOwnProperty检查。