我需要在将被大量使用的代码路径中合并两个对象。该代码有效,但我担心它的速度优化不够,我正在寻找任何改进/替换我提出的建议。我最初在本期结束时开始编写一个示例:如何动态合并两个 JavaScript 对象的属性?. 该解决方案适用于简单对象。但是,我的需求有一个转折点,这就是性能问题的来源。我需要能够支持这样的数组
- 一个简单值数组将在新对象中查找值并将这些值添加到现有对象的末尾,并且
- 对象数组将合并对象(基于 id 属性的存在)或将新对象(id 属性不存在的对象)推送到现有数组的末尾。
我不需要函数/方法克隆,我也不关心 hasOwnProperty,因为对象在合并后会返回 JSON 字符串。
任何帮助我从中提取最后一次性能的建议将不胜感激。
var utils = require("util");
function mergeObjs(def, obj) {
if (typeof obj == 'undefined') {
return def;
} else if (typeof def == 'undefined') {
return obj;
}
for (var i in obj) {
// if its an object
if (obj[i] != null && obj[i].constructor == Object)
{
def[i] = mergeObjs(def[i], obj[i]);
}
// if its an array, simple values need to be joined. Object values need to be remerged.
else if(obj[i] != null && utils.isArray(obj[i]) && obj[i].length > 0)
{
// test to see if the first element is an object or not so we know the type of array we're dealing with.
if(obj[i][0].constructor == Object)
{
var newobjs = [];
// create an index of all the existing object IDs for quick access. There is no way to know how many items will be in the arrays.
var objids = {}
for(var x= 0, l= def[i].length ; x < l; x++ )
{
objids[def[i][x].id] = x;
}
// now walk through the objects in the new array
// if the ID exists, then merge the objects.
// if the ID does not exist, push to the end of the def array
for(var x= 0, l= obj[i].length; x < l; x++)
{
var newobj = obj[i][x];
if(objids[newobj.id] !== undefined)
{
def[i][x] = mergeObjs(def[i][x],newobj);
}
else {
newobjs.push(newobj);
}
}
for(var x= 0, l = newobjs.length; x<l; x++) {
def[i].push(newobjs[x]);
}
}
else {
for(var x=0; x < obj[i].length; x++)
{
var idxObj = obj[i][x];
if(def[i].indexOf(idxObj) === -1) {
def[i].push(idxObj);
}
}
}
}
else
{
def[i] = obj[i];
}
}
return def;}
要合并的对象样本:
var obj1 = {
"name" : "myname",
"status" : 0,
"profile": { "sex":"m", "isactive" : true},
"strarr":["one", "three"],
"objarray": [
{
"id": 1,
"email": "a1@me.com",
"isactive":true
},
{
"id": 2,
"email": "a2@me.com",
"isactive":false
}
]
};
var obj2 = {
"name" : "myname",
"status" : 1,
"newfield": 1,
"profile": { "isactive" : false, "city": "new York"},
"strarr":["two"],
"objarray": [
{
"id": 1,
"isactive":false
},
{
"id": 2,
"email": "a2modified@me.com"
},
{
"id": 3,
"email": "a3new@me.com",
"isactive" : true
}
]
};
一旦合并,这个 console.log(mergeObjs(obj1, obj2)) 应该产生这个:
{ name: 'myname',
status: 1,
profile: { sex: 'm', isactive: false, city: 'new York' },
strarr: [ 'one', 'three', 'two' ],
objarray:
[ { id: 1, email: 'a1@me.com', isactive: false },
{ id: 2, email: 'a2modified@me.com', isactive: false },
{ id: 3, email: 'a3new@me.com', isactive: true } ],
newfield: 1 }