问题描述
如果 title
属性存在,我试图覆盖数组中的对象,否则只需将其推送到数组。我找到了两种方法,不知道哪一种是首选。
性能不是真正的问题,但我想知道可变性是否可以,或者只是有更好的方法来完全做到这一点。
在此代码段中,我使用 for 循环来编辑原始数组:
const data = [
{
title: 'AAA',people: [ 'John','Megan',]
},{
title: 'BBB',people: [ 'Emily','Tom']
}
]
// If inputTitle is not on any of data's title it will append not overwrite
// e.g. const inputTitle = 'CCC'
const inputTitle = 'AAA'
const inputPeople = ['Peter','Jane']
for (const obj of data) {
if (obj.title === inputTitle) {
obj.people = inputPeople
break
} else {
data.push({
title: inputTitle,people: inputPeople
})
break
}
}
console.log(data)
这里我使用高阶函数和传播来做同样的事情:
const data = [
{
title: 'AAA','Jane']
let res = []
if (data.some(({ title }) => title === inputTitle)) {
res = data.map(obj => {
if (obj.title === inputTitle)
obj.people = inputPeople
return obj
})
} else {
res = [...data,{ title: inputTitle,people: inputPeople}]
}
console.log(res)
在实际任务中,我从带有节点的 json 文件中读取 data
数组并将更改写回它。
解决方法
let newdata = {title: 'AAA',people: [ 'Peter','Jane']}
//Create new object
data.find(c => c.title === newdata.title) !== undefined
// if title data from new object is find in old
? data.find(c => c.title === newdata.title).people=newdata.people
// change data
: data.push(newdata)
// in not push it as new
const data = [
{
title: 'CCC',people: [ 'John','Megan']
},{
title: 'BBB',people: [ 'Emily','Tom']
}
]
let newdata = {title: 'AAA','Jane']}
data.find(c => c.title === newdata.title) !== undefined ? data.find(c => c.title === newdata.title).people=newdata.people : data.push(newdata)
console.log(data)
如果这是一个常见的用例,您将在同一个数据结构上执行多次,那么您最好使用以标题为键的普通对象,因为这样操作是微不足道的。您仍然可以将标题也保留为您拥有的属性。
const data = {
AAA: {
title: 'AAA','Megan',]
},BBB: {
title: 'BBB','Tom']
}
};
const title = 'AAA';
const people = ['Peter','Jane'];
data[title] = { title,people }; // yes,it's that simple then...
console.log(data);
如果你真的需要数组结构,那么你可以考虑暂时切换,然后做所有的操作,然后回到原来的格式:
let data = [
{
title: 'AAA','Tom']
}
];
const title = 'AAA';
const people = ['Peter','Jane'];
// switch to other data structure...
let map = Object.fromEntries(data.map(o => [o.title,o]));
// Manipulate
map[title] = { title,people };
// ...and back:
data = Object.values(map);
console.log(data);
如果只需要更新匹配的项目,也许一个forEach
就可以解决这个问题。
const data = [
{
title: 'AAA','Tom']
}
]
const inputTitle = 'AAA'
const inputPeople = ['Peter','Jane']
data.forEach(({ title },index) => title === inputTitle ? data[index].people = inputPeople : null)
console.log(data)