Is map and object same in javascript?

JavaScript map vs object is both data structures with similar concepts but some differences. Using maps in JavaScript, we store data in pairs. Meanwhile, JavaScript objects use key pair values to store data but the key values should be purely integers, strings, and symbols (primitive).

In this guide, we will learn about the differences between these two, so let’s begin!

Contents

• JavaScript Map vs Object Comparison Table
• What Are the Differences Between JavaScript Map vs Object?
• What Is JavaScript Map Best For?
  • – Syntax
• JavaScript Map Methods and Examples
  • – JavaScript Array Map Example
  • – JavaScript Map Object Example
• JavaScript Common Map Methods
  • – JavaScript Additional Map Methods
• What Is JavaScript Object Best For?
  • – Syntax
• JavaScript Objects Methods and Examples
  • – JavaScript Objects Example
  • – JavaScript Objects With More Than One Variable Example
  • – JavaScript Object Literal Example
  • – JavaScript Object Multiple Lines Example
  • – JavaScript Objects Properties Access Example
  • – JavaScript “This” Example
  • – JavaScript Object Methods Access Example
  • – JavaScript Function Definition Example
• FAQs
  • 1. Is It Okay to Declare Strings, Numbers and Booleans as Objects?
  • 2. How Do Map Objects in JavaScript Work?
  • 3. Why Do We Use Maps in JavaScript?
  • 4. How Fast Is a JavaScript Map Compared To a For Loop?
  • 5. Are There Hashmaps in JavaScript?
  • 6. Does the Map Permit Duplicity of Keys in JavaScript?
  • 7. How Is an Object Defined in JavaScript?
  • 8. Are Objects Examples of Hashes in JavaScript?
  • 9. Can We Filter Objects in JavaScript?
• Final Thoughts

JavaScript Map vs Object Comparison Table

Here is a quick table of comparison detailing the differences between JavaScript map vs object.

Comparison	Map	Object
Accidental Keys	No keys by default; only contains the input	Has default values as there is a prototype
Key Types	Values can be functions, objects, or primitive	Can be either string or a symbol
Key Order	Order is simple and values are iterated in the same order they are inserted	The order of ordinary objects is ordered but the order is complex so reliance on the property order is still done carefully
Size	The number of items can be collected from the size property	Manually determined
Iteration	Directly iterable	Not directly iterable and needs Object.keys or Object.entries methods
Performance	Best for times when key-value pairs need to be removed or added	Not suitable for additions or removals of key-value pairs
Serialization and parsing	No native support for serialization or parsing	Native support for serialization through Object to JSON and native support for parsing from JSON to Object

What Are the Differences Between JavaScript Map vs Object?

The main difference between JavaScript map vs object is that the JavaScript object is not ordered and iterable whereas the JavaScript map is both ordered and iterable. Both concepts of maps and objects in JavaScript have subtle but prime differences which should be taken into notice for effective performance during coding.

What Is JavaScript Map Best For?

Use map in JavaScript is best for preventing duplicity as the key pairs are made of unique keys and values that are mapped to the key itself. We must always keep track of these key-value pairs in maps. These keys can have any type of data as the maps recall the initial order of the keys due to a map property that defines the size.

When using map in JavaScript, the order of elements is not affected unlike objects, where the order of the elements may be affected. Also, maps are instances of objects but objects do not comply with this condition.

The biggest advantage of using maps in JavaScript is the usage of keys of any type. Unlike an object’s selective acceptance of keys, maps allow any keys, preserving the order and the key type, an added plus.

– Syntax

let map = new Map([iterable]);

JavaScript Map Methods and Examples

When using map in JavaScript, we use the following methods shown in the table below:

Method Name	Description
new Map()	This is used to create a new map object.
set()	This is used for setting values for a key in a map.
get()	This is used to get values for a key in a map.
clear()	This is used to remove elements (all) from a map.
delete()	This is used to remove an element (map) declared by a key.
has()	If there is a key in a map, the method returns true.
forEach()	Here, callbacks are made for each key or a value pair in a map.
entries()	This works with key or value pairs in a map to return an iterator.
keys()	This is used with the keys in a map to return an iterator object.
values()	This is used with the values of a map to return an iterator object.

– JavaScript Array Map Example

JavaScript Map Objects

In this example, we are creating a map from an array:

• Analysis

From the example above, we used one of the two methods used to create a map in JavaScript; JavaScript array map (newMap()). Using this method, we can add elements to the map.

– JavaScript Map Object Example

JavaScript Map Objects

In this example, we are using the Map.set():

• Analysis

The set() method is shown in the above example. When we use map in JavaScript, this method helps us change the values that pre-exist in the map. An example can be vegetables.set(“spinach”, 100); respectively.

JavaScript Common Map Methods

There are some more methods we use map in JavaScript. These methods are similar to the above examples with changed method names as shown in the table earlier.

• Map.get() method: vegetables.get(“spinach”);
• Map.size() method: vegetables.size;
• Map.delete() method: vegetables.delete(“spinach”);
• Map.clear() method: vegetables.clear();
• Map.has method: vegetables.has(“spinach”); or vegetables.delete(“spinach”); vegetables.has(“spinach”);

– JavaScript Additional Map Methods

• Typeof Method

• The Instanceof Method

vegetables instanceof Map;

• The Map.forEach() Method

let text = “”;
vegetables.forEach (function(value, key) {
text += key + ‘ = ‘ + value;
})

• The Map.Key() Method

let vegetables = “”;
for (const x of vegetables.keys()) {
vegetables += x;
}

• The Map.values() Method

let total = 1;
for (const x of vegetables.values()) {
total += x;
}

• Map.entries() Method

let text = “”;
for (const x of vegetables.entries()) {
text += x;
}

What Is JavaScript Object Best For?

JavaScript objects are best for containing data values with properties which can be weight, height, color, shape, or any other attribute. Objects also have methods such as a pause and play, or a start and stop. Be mindful that not all the properties will be the same for each object and just like that, not all the methods of an object will be the same for the other object in JavaScript.

Objects provide flexibility in the declaration and are convenient as there is less coding needed during the declaration.

– Syntax

JavaScript Objects Methods and Examples

We must remember that objects also have methods just like maps. These methods are performed on the objects as actions and are stored in properties as definitions of functions.

Property	Property Value
firstName	John
lastName	Doe
age	50
eyeColor	blue
fullName	function() {return this.firstName + ” ” + this.lastName;}

– JavaScript Objects Example

JavaScript Variables

• Analysis

The code above is simply assigned a value (Mercedes to the car named variable).

– JavaScript Objects With More Than One Variable Example

JavaScript Objects

• Analysis

We must remember that objects are also deemed as variables but they have values. The example above shows the code assigning more than one value to the variable we had named car in the first example of an object in JavaScript.

Here, the values are in value pairs where the name and the value are selectively parted with a colon.

Do note that most objects are declared with the const keyword.

– JavaScript Object Literal Example

JavaScript Objects

• Analysis

In the above example, we have simply put all our values in a single line but be mindful that where necessary, we must use spaces and line breaks in JavaScript to ensure a tidier code. Do note that spaces and line breaks are not mandatory in JavaScript. We use object literals in JavaScript to create and define an object.

– JavaScript Object Multiple Lines Example

JavaScript Objects

– JavaScript Objects Properties Access Example

JavaScript Objects

In JavaScript, we have two different ways to access an object property.

We can either use person.property or person[“property”].

– JavaScript “This” Example

const person = {
firstName: “John”,
lastName : “Doe”,
id : enteryouridhere,
fullName : function() {
return this.firstName + ” ” + this.lastName;
}
};

• Analysis

For named values known as properties, JavaScript objects act as containers. The usage of “this” represents the person’s object. The mention (this.firstName) means the firstName property of this, which means the firstName property of the person. Do note the following observations about this in JavaScript:

• Normally, this keyword refers to an object.
• When used alone, it is a global object.
• When used in a function, it is a global object.
• In a function’s definition, this represents the owner of a function.

As we can see, this behaves differently according to the given situation. Take note that since this is not a variable, the keyword’s value cannot be altered.

– JavaScript Object Methods Access Example

JavaScript Objects

An object method is a function definition, stored as a property value.

• Analysis

In the example above, we have used parentheses to access the object methods. Not using parentheses will return us a function’s definition.

– JavaScript Function Definition Example

JavaScript Objects

As we mentioned, if we access an object method without (), it will return the function definition:

FAQs

Here are some answers to your questions about JavaScript Maps vs Objects.

1. Is It Okay to Declare Strings, Numbers and Booleans as Objects?

No, because all three types make the code complex and the overall execution speed is affected.

2. How Do Map Objects in JavaScript Work?

Each element in a map is stored as a key that forms a collection, and the map on a string passes an argument of the function, working like a split() method of a string where each string character can be modified. The map object can hold both objects as keys or values. Iteration of the map object returns us the key and the value pair in the default order.

3. Why Do We Use Maps in JavaScript?

The map() method is used to create arrays by calling functions on each element present in the parent array. This is a general practice where we iterate over an array and call a function over elements of the array.

4. How Fast Is a JavaScript Map Compared To a For Loop?

The for loop is 250 ms whereas 2,000 ms is recorded for map().

5. Are There Hashmaps in JavaScript?

Yes, in JavaScript, there is no hashtable class but there are native objects or maps (hashmaps) offering functionality to keep the key and value pairs organized.

6. Does the Map Permit Duplicity of Keys in JavaScript?

No, maps accept all types of data as keys but they do not permit the duplicity of keys or values.

7. How Is an Object Defined in JavaScript?

The object is defined by the object’s collection of properties and the relation between the name and values. Do remember that the property can be a function and if that is the case, it is a method.

8. Are Objects Examples of Hashes in JavaScript?

Yes, because the data represented is of key or value pairs, denoting the hash table nature. We can also use the hashing function to map the keys to the index by using inputs and hash code identifiers of fixed sizes.

9. Can We Filter Objects in JavaScript?

In JavaScript, we do not have a filter() function but by iteration over an object and conversion of the object into an array, we can utilize the filter() for the objects in JavaScript.

Final Thoughts

As shown in the detailed comparison above, both maps and objects store key values but objects keys are limited to strings or symbols and integers whereas maps accepts all key types. The different methods and examples used above and the detailed FAQs help us solve the common questions that arise when discussing maps and objects in JavaScript. Among both methods, both have their own importance.

We use maps when keys are the same type or the values are unknown until the runtime, and when there are individual elements, using objects is much better. Thus, it depends and we should use both methods according to the situation. Do note that maps have the edge over objects because they can create hashmaps. To learn more about hashmaps, visit our blog.

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