将数组[{key: "aaa", value: "aaa1"},{key: "bbb", value: "bbb1"}]转化为字符串 aaa:aaa1,bbb:bbb1

arr.map(({key, value}) => `${key}:${value}`).join(',')

// result => "aaa:aaa1,bbb:bbb1"
var result = [{key: "aaa", value: "aaa1"},{key: "bbb", value: "bbb1"}].reduce(function (str, item) {
  str += `${str=='' ? '' : ','}${item.key}:${item.value}`;
  return str;
}, '');