js改变对象的key，把key替换成想要的key，值不变
例如把接口返回对象data {id：“11”,name:“张三”} 的key值替换成 {序列：“11”,姓名：“张三” }
data {id：‘11’,name:‘张三’}
var keyMap = {id: ‘序列’, name: ‘姓名’}
var objs= Object.keys(data).reduce((newData, key) => {
let newKey = keyMap[key] || key
newData[newKey] = data[key]
return newData
}, {})
alert(objs)
data对象就变成了 {序列：“11”,姓名：“张三” }
该方法可随意替换对象的key值，对对象属性数量、排序无要求
原文链接：https://blog.csdn.net/w19970824/article/details/88060209
var obj = {
"a":"nihoa", //和这样写法的区别
b:"wobuhoa", //注意这样的写法
"c":"lalala"
}
var arr = ['a',"b",3,4,5]
var zzz = arr[1];
console.log(zzz); //取到b
console.log(obj.zzz); //这样取到undefined
console.log(obj[zzz]) //正确取到wobuhoa
console.log(obj["a"]) //正确取到nihoa
console.log(obj.a) //正确取到nihoa
console.log("___________________________________________")
console.log(obj.a); //nihoa
console.log(obj.b); //wobuhoa
console.log(obj.c); //lalala
image.png
var obj ='{"a":"nihoa","b":"wobuhoa","c":"lalala"}'
console.log(JSON.parse(obj))
var json = {result:true, count:42};
console.log(JSON.stringify(json))
image.png
第一种形式 [[ ]]
[["12","32","56","10","67","89","12","12","8","42","33","9"]]
怎么处理上面的数据，处理以后是以下的形式；因为我要在页面上循环遍历
["12","32","56","10","67","89","12","12","8","42","33","9"]
解决方案 eval(数据)
eval(数据)可以对数据进行运算，例如返回数组对象，自动去掉外面多于的[]
this.tableData=eval(e.data);
第二种形式 {"属性名":"属性值"}
{"sz":["12","32","56","10","67","89","12","12","8","42","33","9"]}
我要获取["12","32","56","10","67","89","12","12","8","42","33","9"]
解决方案
var obj = eval('(' + e.data + ')');
alert(obj.sz);
this.tableData=obj.sz;
改变key
let arr=[{evaluateResult: "A类", evaluateTotal: 22},{evaluateResult: "B类", evaluateTotal: 22}]
let keyMap = {evaluateResult: 'name', evaluateTotal: 'value'}
arr.map(item=>{
var objs= Object.keys(item).reduce((newData, key) => {
let newKey = keyMap[key] || key
newData[newKey] = item[key]
return newData
}, {})
console.log(objs)
})
## [JS数组reduce()方法](https://www.cnblogs.com/zhaofeis/p/10620226.html)
arr.reduce(function(prev,cur,index,arr){
...
}, init);
或者
arr.reduce(function(prev,cur,index,arr){
...
},);
**arr** 表示将要原数组；
**prev** 表示上一次调用回调时的返回值，或者初始值 init;
**cur** 表示当前正在处理的数组元素；
**index** 表示当前正在处理的数组元素的索引，若提供 init 值，则索引为0，否则索引为1；
**init** 表示初始值。
常用的参数只有两个：**prev** 和 **cur**。
数组求和，求乘积
var arr = [1, 2, 3, 4];
var sum = arr.reduce((x,y)=>x+y)
var mul = arr.reduce((x,y)=>x*y)
console.log( sum ); //求和，10
console.log( mul ); //求乘积，24
计算数组中每个元素出现的次数
let names = ['Alice', 'Bob', 'Tiff', 'Bruce', 'Alice'];
let nameNum = names.reduce((pre,cur)=>{
if(cur in pre){
pre[cur]++
}else{
pre[cur] = 1
}
return pre
},{})
console.log(nameNum); //{Alice: 2, Bob: 1, Tiff: 1, Bruce: 1}数组去重
let arr = [1,2,3,4,4,1]
let newArr = arr.reduce((pre,cur)=>{
if(!pre.includes(cur)){
return pre.concat(cur)
}else{
return pre
}
},[])
console.log(newArr);// [1, 2, 3, 4]
let arr = [[0, 1], [2, 3], [4, 5]]
let newArr = arr.reduce((pre,cur)=>{
return pre.concat(cur)
},[])
console.log(newArr); // [0, 1, 2, 3, 4, 5]
let arr = [[0, 1], [2, 3], [4,[5,6,7]]]
const newArr = function(arr){
return arr.reduce((pre,cur)=>pre.concat(Array.isArray(cur)?newArr(cur):cur),[])
}
console.log(newArr(arr)); //[0, 1, 2, 3, 4, 5, 6, 7]
var result = [
{
subject: 'math',
score: 10
},
{
subject: 'chinese',
score: 20
},
{
subject: 'english',
score: 30
}
];
var sum = result.reduce(function(prev, cur) {
return cur.score + prev;
}, 0);
console.log(sum) //60
改变对象key的位置
var data = {
first: {
'name': 'zhangsan',
'id': 99,
'sex': 'nan',
'age': 19,
},
second: {
'name': '李四',
'sex': '女',
'id': 108,
'age': 25
}
}
var obj = {};
for(var i in data) {
obj = {
"id": data[i]['id'],
"name": data[i]['name'],
"age": data[i]['age'],
'sex': data[i]['sex']
}
data[i] = obj;
}
console.log(data);
