编写findMatches函数：筛选数组中匹配指定键值对的对象并返回数组

To solve this problem, we need to filter an array of objects to retain only those that fully contain all key-value pairs from the provided match rule object. Here's a clean, robust implementation:

function findMatches(arr, obj) {
  // Convert the match rule object into an array of [key, value] pairs
  const matchEntries = Object.entries(obj);
  
  // Filter the input array to keep only objects that match all rules
  return arr.filter(item => {
    // Verify every key-value pair from the rule exists and matches in the current item
    return matchEntries.every(([key, value]) => item[key] === value);
  });
}

How It Works #

Let’s break down the logic step by step:

1. Extract Match Rules: Object.entries(obj) transforms the match rule object into an array of key-value pairs. For your sample input, this becomes [["X", "1"], ["Y", "2"]].
2. Filter the Array: We use arr.filter() to loop through each object in the input array. For each object:
   • matchEntries.every(...) checks if all key-value pairs from the rule are present and equal in the current item. If even one pair doesn’t match, the object is excluded from the result.

Example Test #

Let’s run your sample input through the function:

const inputArr = [
  {"X" : "1", "Y" : "2","Z" : "4", "P" : "5"},
  {"X" : "2", "Y" : "2","Z" : "4", "P" : "5"},
  {"X" : "1", "Y" : "2","Z" : "9", "P" : "6"}
];
const matchObj = {"X":"1", "Y":"2"};

console.log(findMatches(inputArr, matchObj));

Output:

[ {"X" : "1", "Y" : "2","Z" : "4", "P" : "5"}, {"X" : "1", "Y" : "2","Z" : "9", "P" : "6"} ]

Which matches exactly what you expected!

Edge Cases Handled #

• Empty match object: If obj is empty, the function returns the entire input array (since every object trivially contains zero key-value pairs).
• Empty input array: Returns an empty array, as there’s nothing to filter.
• Match object with multiple keys: Works regardless of how many key-value pairs you need to check.
• Non-existent keys: If an object in arr doesn’t have a key from obj, item[key] will be undefined, which won’t match the rule’s value, so it gets excluded.

This implementation is concise, readable, and handles all valid input scenarios as required.

内容的提问来源于stack exchange，提问作者Anistan Yoganath