for in / for of
function params (){
var data = {
'成都威威': [20, 30, 10],
'上海11': [20, 10, 60],
'北京': [20, 10, 60],
'杭州': [20, 10, 30]
}
var newData = {}
var newDatas={}
let newKeys = Object.keys(data)
newKeys.map((item,idx)=>{
if(idx < 3){
newData[item] = data[item]
}
})
for (let key in newData){
let newKey = key.substring(0,2)
newDatas[newKey] = newData[key]
}
console.log(newDatas)
//for in 循环key for of 循环value
}
params()