How to Update the Value for a Key in a Map in JavaScript

How to Update the Value for a Key in a Map in JavaScript ?

Answer

To update the value for a key in a map in JavaScript, you can use the set method. This method allows you to modify the value associated with a specific key directly.

✐ Examples

1 Updating the Value Using set Method

We can update the value for a key in a map in JavaScript using the set method, which allows us to modify the value associated with a specific key directly.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the set method to update the value for a specific key in the map. The set method takes the key and the new value to be assigned.
We print the updated map to the console using the forEach method and console.log.

JavaScript Program

const myMap = new Map([
    ['one', 1],
    ['two', 2],
    ['three', 3]
]);

// Update the value using set method
myMap.set('two', 22);

// Print the updated map
myMap.forEach((value, key) => {
    console.log(`${key}: ${value}`);
});

Output

one: 1
two: 22
three: 3

2 Updating the Value Conditionally Using set Method

We can update the value for a key in a map in JavaScript using the set method conditionally, which updates the value only if the key exists.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use an if statement to check if the key exists in the map. If the key exists, we use the set method to update the value.
We print the updated map to the console using the forEach method and console.log.

JavaScript Program

const myMap = new Map([
    ['one', 1],
    ['two', 2],
    ['three', 3]
]);

// Update the value conditionally using set method
if (myMap.has('two')) {
    myMap.set('two', 22);
}

// Print the updated map
myMap.forEach((value, key) => {
    console.log(`${key}: ${value}`);
});

Output

one: 1
two: 22
three: 3

3 Updating Multiple Values Using set Method

We can update multiple values for keys in a map in JavaScript using the set method.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the set method to update the values for specific keys in the map. The set method takes the key and the new value to be assigned.
We print the updated map to the console using the forEach method and console.log.

JavaScript Program

const myMap = new Map([
    ['one', 1],
    ['two', 2],
    ['three', 3]
]);

// Update multiple values using set method
myMap.set('two', 22);
myMap.set('three', 33);

// Print the updated map
myMap.forEach((value, key) => {
    console.log(`${key}: ${value}`);
});

Output

one: 1
two: 22
three: 33

Summary

In this tutorial, we learned How to Update the Value for a Key in a Map in JavaScript language with well detailed examples.

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How to Update the Value for a Key in a Map in JavaScript