[英]array.map is mutating my original array
I am trying to update a field in an object in my array. 我正在尝试更新数组中对象的字段。
My object (simplified) looks something like this: 我的对象(简化)看起来像这样:
{
"readableStructure": [
{
"ID": "1",
"Name": "Name 1",
"Description": "Adding, updating or removing users",
"IconName": "fas fa-users-cog"
},
{
"ID": "2",
"Name": "Name 2",
"Description": "Views overview",
"IconName": "fas fa-street-view"
},
{
"ID": "3",
"Name": "Name 3",
"Description": "Improvements to apps",
"IconName": "fas fa-broadcast-tower"
},
{
"ID": "4",
"Name": "Name 4",
"Description": "Managing badges",
"IconName": "fas fa-id-badge"
},
{
"ID": "5",
"Name": "Name 5",
"Description": "Art",
"IconName": "fas fa-hand-holding-heart"
}
]
}
and I call it like this: 我这样称呼它:
prepareRepositories(this.props.primarySearchRepositories);
I can have several similar repos and I loop through them. 我可以有几个类似的存储库,并遍历它们。 And for each item in the array
readableStructure
I am trying to add a property called QSString
using the following code. 而对于在阵列中的每个项目
readableStructure
我想添加一个名为属性QSString
使用下面的代码。
prepareRepositories(repositories) {
const repos = repositories.map((repo, index) => {
const searchableColumns = ['Name', 'Description'];
const newRepo = [];
newRepo[0] = {};
newRepo[0].readableStructure = [];
newRepo[0].readableStructure = repo[0].readableStructure.map((item) => {
item.QSString = this.getSearchableString(item, searchableColumns) || 'blaha';
return item;
});
return newRepo;
});
return repos;
}
getSearchableString = (base, searchableColumns) => {
let searchables = [];
Object.keys(base).forEach((key) => {
if ((searchableColumns.indexOf(key) > -1) && (base[key] !== null) && (typeof base[key] !== 'object')) {
searchables.push(base[key]);
}
});
const searchableString = searchables.join(' ');
return searchableString;
}
However, when I do this the original object is modified and the QSString
property get set to the same thing for every repo. 但是,当我这样做时,原始对象将被修改,并且每个
QSString
属性都设置为相同的东西。
What am I doing wrong? 我究竟做错了什么?
Array.map does not change the original array, ie creates a new Array. Array.map不会更改原始数组,即创建一个新的Array。 However, any object in the Array continues to hold the same reference , hence, any change in object even inside map function will update the object in original array.
但是,数组中的任何对象继续保持相同的引用 ,因此,即使在map函数内部,对象中的任何更改都将更新原始数组中的对象。
You need to create a copy for the object . 您需要为该对象创建一个副本 。
item = JSON.parse(JSON.stringify(item))
使用这个不会改变原始对象
JSON.parse(JSON.stringify(your_object))
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.