1. Array 转Map
// create array data
let arr = [
{type:'1',name:'name1'},
{type:'2',name:'name2'}
];
// convert array data to map
let map = new Map(arr.map(i =>[i.type,i]));
2. Array reduce sum
// create array data
let arr = [
{type:'1',count:1},
{type:'2',count:2}
];
// sum count value
let sum = reduce((accumulator, currentValue)=>accumulator+currentValue.count,0);