如何迭代以数组为值的对象

Question

For Example :

I have an object and in that object, I have values in the array. I want to return the array which contains the key which contains the value passing as a variable.

 function getValues(val , object){
  return []; // return [b,c] because xyz are present in both
}

var object = {
     "a" : ["abc", "cde","efg"],
     "b" : ["asdf","asee","xyz"],
     "c" : ["asaw","wewe","xyz"]

  getValues("xyz", object);
}```

Answer 1

There are various ways to approach this.
One could be using Object 's native functions:

function getValues(str, obj) {
  return Object
     // returns the entries pairs in a array of [key, value]
    .entries(obj)
    // from the array it searches the value for the string inputted and maps it back
    .map(([key, array]) => array.includes(str) ? key : undefined)
    // simply remove the undefined returned values from map()
    .filter((value) => value);    
};

This could have been done with reduce() as well but I found it easier to explain this way.

Another approach is using a for loop to iterate over the keys of the object:

function getValues(str, obj) {
  let arr = [];
  // Iterates through the object selecting its keys
  for (let key in obj) {
    // If the array of the current key has the string in it, includes in the array
    if (obj[key].includes(str)) {
      arr.push(key)
    }
  }
  return arr;
}