If you are looking for a method for defining and using key-value pair in Typescript, consider referring to the method we have given below. Now let’s start by preparing pen and paper and read this article.

Defining and using key-value pair in Typescript – What should we do?

A key-value pair is a pair of related bits of data. The data is identified, or a pointer to that data is referred to as a value. A key is a particular identifier that points to its associated value.

In URLs, key-value pairs are separated by the ampersand “&.” An equal sign, “= separate each key-value pair.” Suppose with the URL: “https://www.example.com/?key1=value1&key2=value2”, the first key-value pair is key1=value1, and the second key-value pair (key) -value pair) is key2=value2.

The method for defining and using key-value pair in Typescript is to use the index signature.

The syntax of a signature is not so complicated and even resembles the syntax of an attribute. However, you may just insert the key type inside square brackets in place of the property name.

{ [key: KeyType]: ValueType }:

The way you configure the index signature will be determined based on the available information about the object’s shape.

You may configure the index signature as shown above since you already know that the “key” type in the example is a number and the “value” type is a string.

interface UserType {

  [index: number]: string;

}

const user: UserType = { 1: "Sharooq", 2: "23" };

The index signature in this example will be more precise, with the “key” type being a string and the “value” type being a string. The code below will produce an error.

interface UserType {

  [index: string]: string;

 }

 const user: UserType = { name: "Sharooq", age: 23 }; // Type 'number' is not assignable to type 'string'.

The error message for the code as mentioned above is “Type ‘number’ is not assignable to type string.'”

Type 'number' is not assignable to type 'string'

    }

    const user: UserType = { 1: "Sharooq", 2: 23 } ;

    return (

      <div className="App">

The union operator is applicable here. Syntax of the index signature:

  interface UserType {

    [index: string]: string | number;

  }

  const user: UserType = { name: "Sharooq", age: 23 }; // error resolved

We specified the “value” type as a number or a string. To be more detailed, you might define any individual property. Example:

interface UserType {

  [index: string]: string | number;

  age: number; //age will only accept number

}

const user: UserType = { name: "Sharooq", age: 23 };

Thanks for this; the object that you know the exact type of is guaranteed to be typed and checked by Typescript.

Conclusion

Thank you for taking the time to read the article. ITtutoria hopes that the method for defining and using key-value in Typescript that we give will be useful to you. Don’t forget to leave your thoughts and opinions below in the comments section. Good luck!

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→ Tips to Add Key Value Pair Java – A Complete Guide