node.js中的数组比较

Question

考虑我有2个数组如下：

Array1 = ["123","234"] 

Array2 = [{"keyA":"123","keyB":"rtefre"},{"keyA":"789","keyB":"sdfs"}, {"keyA":"234","keyB":"tyrvfd"}]

我必须将Array1字符串与Array2中的keyA进行比较，并获取所有这些细节。

我的结果如下：

[{"keyA":"123","keyB":"rtefre"}, {"keyA":"234","keyB":"tyrvfd"}]

我必须尽可能避免使用For循环。请分享您的想法。提前谢谢。

Answer 1

怎么样

filteredArray = Array2.filter(item => Array1.indexOf(item.KeyA) !== -1);

另外，假设它在节点中运行，我假设你可以访问这里使用的一些es6细节（箭头函数和原生过滤器）

Answer 2

您可以使用哈希表并过滤项目。

var array1 = ["123", "234"],
    array2 = [{ "keyA": "123", "keyB": "rtefre" }, { "keyA": "789", "keyB": "sdfs" }, { "keyA": "234", "keyB": "tyrvfd" }],
    hash = Object.create(null),
    result;

array1.forEach(a => hash[a] = true);
result = array2.filter(a => hash[a.keyA]);
console.log(result);

Answer 3

如果要考虑效果，那么您应该避免indexOf并做一些比这更聪明的事情......即：排序Array1 并执行二进制搜索< /强>

我建议使用javascript对象。 所以解决方案如下......

var Array1 = ["123","234"]
var Array2 = [{"keyA":"123","keyB":"rtefre"},
              {"keyA":"789","keyB":"sdfs"}, 
              {"keyA":"234","keyB":"tyrvfd"}]
var map=Array1.reduce(function(prev,current){
  prev[current]=true;
  return prev;
},{});//Creating object to find out if the element exist or not

Array2 = Array2.filter(function(item){
  return !!map[item["keyA"]];//filtering elements which are not in map.
});
console.log(Array2);