Using JavaScript Objects as Key-Value Store – TecAdmin

Channel: Linux
Abstract: console.log(person.age)and person[key] gives us the value associated with that key. Caveats and Considerations While using JavaScript objects as a sim

JavaScript objects are versatile data structures that provide a simple and effective way to store data as key-value pairs. The keys are always strings, while the values can be any type of data such as strings, numbers, arrays, other objects, or even functions. This article will walk you through how to use JavaScript objects as a simple key-value store, with practical examples for better understanding.

What is a Key-Value Store?

A key-value store is a simple database that uses an associative array as the fundamental data model. This structure consists of a collection of key-value pairs in which each key is unique. Key-value stores are used for various applications, including caching, session management, and other cases where quick lookups of data are necessary.

JavaScript Objects as a Key-Value Store

In JavaScript, objects are collections of properties. Each property is a key-value pair. Keys (also known as property names) are strings, while the value can be anything.

Let’s look at an example:

let person = {
    name: "Alice",
    age: 25,
    profession: "Software Developer"

In this person object, name, age, and profession are keys, and 「Alice」, 25, and 「Software Developer」 are their corresponding values.

Operations on Key-Value Store1. Adding Key-Value Pairs

You can add key-value pairs to an object using the dot (.) notation or the bracket ([]) notation. Here’s how:

  • Dot notation:
    person.nationality = "American";
  • Bracket notation:
    person["nationality"] = "American";
2. Reading Values

You can read a value associated with a key using the same notations.

  • Dot notation:
    console.log(; // Alice
  • Bracket notation:
    console.log(person["name"]); // Alice
3. Updating Values

Updating a value associated with a key is as simple as adding a key-value pair. If the key already exists in the object, its value will be updated.

person.age = 26;
console.log(person.age); // 26

4. Deleting Key-Value Pairs

You can delete a key-value pair from an object using the delete operator.

delete person.age;
console.log(person.age); // undefined

5. Checking for Keys

To check whether a key exists in an object, you can use the hasOwnProperty method or the in operator.

console.log(person.hasOwnProperty("name")); // true
console.log("name" in person); // true

6. Iterating Over Key-Value Pairs

You can iterate over key-value pairs in an object using a for…in loop.

for (let key in person) {
    if (person.hasOwnProperty(key)) {
        console.log(key + ": " + person[key]);

In the code snippet above, key iterates over the keys in the person object, and person[key] gives us the value associated with that key.

Caveats and Considerations

While using JavaScript objects as a simple key-value store is straightforward, there are a few things to keep in mind:

  1. Keys are always converted to strings. This can lead to unexpected results if you’re not careful. For example, the number 123 and the string 「123」 will be considered the same key.
  2. The order of properties in an object is not guaranteed in older JavaScript standards (ES5 and below), but is preserved in ES6 and later versions.
  3. JavaScript objects come with built-in properties and methods, which may interfere with your keys. Always check for potential naming conflicts to avoid overwriting or calling unexpected methods or properties.

In conclusion, JavaScript objects provide a simple and effective way to create a key-value store, accommodating a wide range of data types as values. While they lack the performance and feature set of a full-fledged key-value store database, they can be the perfect solution for simple use cases.

Ref From: tecadmin

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