In this article, we will see different approaches to update the value for a specific key in Map in JavaScript. JavaScript Map is a collection of key-value pairs. We have different methods to access a specific key in JavaScript Map.
Methods to update the value for a specific key in Map in JavaScript
- Using the JavaScript Map set() Method
- Using Map.forEach() Method
Method 1: Using JavaScript Map.set() method
In this method, we will use the built-in Map.set() method to update the value for a specific key.
Example: In this example. we will update the value of key(‘b’) in the given map using the map.set() method.
Javascript
let m = new Map([
["a", 100],
["b", 200],
]); console.log("Old value for key: 'b', "+m.get('b'));
m.set('b',1000)
console.log("New value for key: 'b', "+m.get('b'));
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Output
Old value for key: 'b', 200 New value for key: 'b', 1000
Method 2: Using Map.forEach() method
In this method, we will iterate the map using map.forEach() method to iterate the key-value pairs and update the value for specific key.
Example: In this example, we will iterate map using forEach method and update the value for a specific key using if condition.
Javascript
// Creating a map object let m = new Map([
["a", 100],
["b", 200],
]); // Display old value console.log("Old value for key: 'b', " + m.get("b"));
// Iterate and change the required value m.forEach((value, key) => { if (key == "b") m.set(key, 1000);
}); // Display updated value console.log("New value for key: 'b', " + m.get("b"));
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Output
Old value for key: 'b', 200 New value for key: 'b', 1000