How to use Associative Array in TypeScript ?

Last Updated : 05 Apr, 2024

Typescript Associative arrays are objects in which indexes are replaced by user-defined keys. Associative Array can be used like a regular array, but the only difference is that it can be accessed using strings instead of numbers.

Syntax:

let associativeArray: { [key: string]: string } = {
    key1: "value1",
    key2: "value2",
};

console.log(associativeArray['key1']);
// Output: value1

Example 1: To demonstrate creating and accessing values in an associative array using TypeScript.

JavaScript

let fruitMap:
    {
        [key: string]: string
    } =
{
    "apple": "red",
    "banana": "yellow",
    "grapes": "green"
};

// Adding elements to the associative array
fruitMap["orange"] = "orange";

// Printing the keys of the associative array  
console.log("Keys are listed below:");
console.log(Object.keys(fruitMap));

// Accessing values using keys
console.log("Color of apple:", fruitMap["apple"]);
console.log("Color of banana:", fruitMap["banana"]);
console.log("Color of grapes:", fruitMap["grapes"]);
console.log("Color of orange:", fruitMap["orange"]);

Output:

Keys are listed below:
[ 'apple', 'banana', 'grapes', 'orange' ]
Color of apple: red
Color of banana: yellow
Color of grapes: green
Color of orange: orange

Example 2: To demonstrate iterating over keys and values in an associative array in TypeScript.

JavaScript

let fruitMap:
    {
        [key: string]: string
    } =
{
    "apple": "red",
    "banana": "yellow",
    "grapes": "green"
};

// Adding elements to the associative array
fruitMap["orange"] = "orange";

// Iterating over keys and 
// values in the associative array
console.log("Iterating over keys and values:");
for (let key in fruitMap) {
    if (fruitMap.hasOwnProperty(key)) {
        console.log("Key:", key, ", Value:", fruitMap[key]);
    }
}

Output:

Iterating over keys and values:
Key: apple , Value: red
Key: banana , Value: yellow
Key: grapes , Value: green
Key: orange , Value: orange

Example 3: To demonstrate removing an element from an associative array in TypeScript.

JavaScript

// Creating an associative 
//array (object) in TypeScript
let fruitMap: { [key: string]: string } =
{
  "apple": "red",
  "banana": "yellow",
  "grapes": "green"
};

// Removing an element 
// from the associative array
delete fruitMap["grapes"];
console.log("After removing 'grapes':",
  Object.keys(fruitMap));

Output:

After removing 'grapes': [ 'apple', 'banana' ]

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