Question

在JavaScript中，我有一个由三个字母代码组成的数组，并且有一个JSON文件，其中包含每个代码的值。我需要将代码映射到JSON文件中的相应值。这是一个示例：

{"Roles" : [
{"code": "cmm", "fullname": "commentator"},
{"code": "cmp", "fullname": "composer"},
{"code": "cnd", "fullname": "conductor"},
{"code": "cng", "fullname": "cinematographer"},
{"code": "cns", "fullname": "censor"},
{"code": "com", "fullname": "compiler"}
]}

var arr = ["cmm", "com", "cng"];
var mappedArray = arr.map( ??? );

//mappedArray now contains: ["commentator", "composer", "cinematographer"]

我想不出一种解决方法，该方法并非效率极低。有人可以帮忙吗？

Answer 1

您可以使用filter

var obj = {"Roles" : [
{"code": "cmm", "fullname": "commentator"},
{"code": "cmp", "fullname": "composer"},
{"code": "cnd", "fullname": "conductor"},
{"code": "cng", "fullname": "cinematographer"},
{"code": "cns", "fullname": "censor"},
{"code": "com", "fullname": "compiler"}
]}

var arr = ["cmm", "com", "cng"];

var mappedArray = obj["Roles"].filter(d => arr.includes(d.code))

console.log('Filtered Array', mappedArray)

console.log('Result', mappedArray.map(({fullname}) => fullname))

Answer 2

最有效的方法仍然是使用for/loop：

const data = {"Roles" : [{"code": "cmm", "fullname": "commentator"},{"code": "cmp", "fullname": "composer"},{"code": "cnd", "fullname": "conductor"},{"code": "cng", "fullname": "cinematographer"},{"code": "cns", "fullname": "censor"},{"code": "com", "fullname": "compiler"}]};
var arr = ["cmm", "com", "cng"];

const out = [];
for (let i = 0; i < data.Roles.length; i++) {
  const el = data.Roles[i];
  if (arr.indexOf(el.code) > -1) out.push(el.fullname);
}

console.log(out);

使用reduce更具功能/外观，但效率不高。您可以使用filter 然后 map来回提取所需的数据。

const data = {"Roles" : [{"code": "cmm", "fullname": "commentator"},{"code": "cmp", "fullname": "composer"},{"code": "cnd", "fullname": "conductor"},{"code": "cng", "fullname": "cinematographer"},{"code": "cns", "fullname": "censor"},{"code": "com", "fullname": "compiler"}]};
var arr = ["cmm", "com", "cng"];

var out = data.Roles.reduce((acc, c) => {
  if (arr.includes(c.code)) acc.push(c.fullname);
  return acc;
}, []);

console.log(out);

Answer 3

您必须首先过滤数组，然后将其映射以获取所需的值。你可以试试这个

TextView,ButtonView

使用JSON文件的JavaScript地图数组

3 个答案: