Find Matching Keys in JavaScript Objects

Introduction

In this lab, we will explore how to find all the keys in a JavaScript object that match a given value. By using Object.keys() and Array.prototype.filter(), we can efficiently search through an object and return an array of keys that correspond to the provided value. This will be a valuable skill for any JavaScript developer working with complex data structures.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL javascript(("JavaScript")) -.-> javascript/AdvancedConceptsGroup(["Advanced Concepts"]) javascript(("JavaScript")) -.-> javascript/BasicConceptsGroup(["Basic Concepts"]) javascript/BasicConceptsGroup -.-> javascript/variables("Variables") javascript/BasicConceptsGroup -.-> javascript/data_types("Data Types") javascript/BasicConceptsGroup -.-> javascript/arith_ops("Arithmetic Operators") javascript/BasicConceptsGroup -.-> javascript/comp_ops("Comparison Operators") javascript/BasicConceptsGroup -.-> javascript/array_methods("Array Methods") javascript/AdvancedConceptsGroup -.-> javascript/higher_funcs("Higher-Order Functions") subgraph Lab Skills javascript/variables -.-> lab-28308{{"Find Matching Keys"}} javascript/data_types -.-> lab-28308{{"Find Matching Keys"}} javascript/arith_ops -.-> lab-28308{{"Find Matching Keys"}} javascript/comp_ops -.-> lab-28308{{"Find Matching Keys"}} javascript/array_methods -.-> lab-28308{{"Find Matching Keys"}} javascript/higher_funcs -.-> lab-28308{{"Find Matching Keys"}} end

Find Matching Keys

To find all the keys in an object that match a given value, follow these steps:

Open the Terminal/SSH and type node to start practicing coding.
Use Object.keys() to get all the properties of the object.
Use Array.prototype.filter() to test each key-value pair and return all keys that are equal to the given value.

Here's an example function that implements this logic:

const findKeys = (obj, val) =>
  Object.keys(obj).filter((key) => obj[key] === val);

You can use this function like this:

const ages = {
  Leo: 20,
  Zoey: 21,
  Jane: 20
};
findKeys(ages, 20); // [ 'Leo', 'Jane' ]

Summary

Congratulations! You have completed the Find Matching Keys lab. You can practice more labs in LabEx to improve your skills.