find the key associated with a value in a map in javascript

To find the key associated with a value in a map in JavaScript, you can use a loop to iterate over the key-value pairs in the map and compare the values until you find the one you're looking for. Here's an example:

index.tsx
const myMap = new Map();
myMap.set('apple', 1);
myMap.set('banana', 2);
myMap.set('orange', 3);

function getKeyByValue(map, value) {
  for (let [key, val] of map) {
    if (val === value) {
      return key;
    }
  }
}

console.log(getKeyByValue(myMap, 2)); // Output: 'banana'
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In this example, we have a map called myMap with three key-value pairs. We define a function called getKeyByValue that takes a map and a value as arguments, and returns the key associated with that value. The function loops over the key-value pairs in the map using for..of, and checks each value against the one we're looking for. If it finds a match, it returns the corresponding key.

To use the function, we pass in our map and the value we want to find the key for. The function returns the key 'banana', since that's the key associated with the value 2 in the map.