js快速替换json里的key值

需求是将b根据a的值替换对象中的key值
let a = ["code","name","date","font"];
let b = [{1:2,2:3,3:4},{1:2,2:3,3:4},{1:2,2:3,3:4}];

//[{'code':2,'name':3,'date':4},{'code':2,'name':3,'date':4},{'code':2,'name':3,'date':4}];

let c = b.map((item, index, arr) => {
    let obj = {};
    for(let i in item){
       obj[a[i]] = item[i];
    }
    return obj;
});
console.log(c);//  [{'code':2,'name':3,'date':4},{'code':2,'name':3,'date':4},{'code':2,'name':3,'date':4}];