JavaScript Hashmap Equivalent

In JavaScript, the closest equivalents to a HashMap (from other languages like Java or C++) are:

• Object – a collection of key–value pairs where keys are strings or symbols.
• Map – introduced in ES6, allows keys of any type and maintains insertion order.

Option 1: Using Object (Traditional):

const userDetails = {
 name: "Alice",
 age: 30,
 role: "Developer"
};
// Accessing values
console.log(userDetails["name"]); // Alice

// Adding a new key
userDetails["location"] = "New York";

// Iterating
for (const key in userDetails) {
 console.log(`${key}: ${userDetails[key]}`);
}

Option 2: Using Map (Recommended for most use-cases)

const userMap = new Map();
// Setting key-value pairs
userMap.set("name", "Bob");
userMap.set("age", 25);
userMap.set("role", "Designer");

// Getting values
console.log(userMap.get("name")); // Bob
// Checking if a key exists
console.log(userMap.has("age")); // true
// Iterating
userMap.forEach((value, key) => {
 console.log(`${key}: ${value}`);
});

Summary

Use Map if:

• You need keys other than strings.
• You care about insertion order.
• You want better built-in iteration and performance.

 
Use Object if:

• You only need simple key-value pairs with string keys.
• You need to serialize easily using JSON.