how to use the issymbol function from the underscore library in typescript

To use the _.isSymbol function from the Underscore.js library in TypeScript, first make sure to install and add the Underscore.js library to your TypeScript project. Once that is done, you can import the function from the library and use it in your TypeScript code as shown below:

index.ts
import * as _ from 'underscore';

const symbol = Symbol('mySymbol');
const otherValue = 'test';

console.log(_.isSymbol(symbol)); // true
console.log(_.isSymbol(otherValue)); // false
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In this example, we import the Underscore.js library using the * as _ syntax to create a shorthand for the library name. We then declare a symbol variable using the built-in JavaScript Symbol function and a otherValue variable containing a string. Finally, we use the _.isSymbol function to check if the symbol variable is a symbol or not, and log the result to the console.

Note that to use Underscore.js functions in TypeScript, you may need to install type definitions for the library. Type definitions are files that describe the shape and types of a given JavaScript library, and they help TypeScript understand how to work with the library. You can install type definitions for Underscore.js using a package manager like npm or yarn. Once you have installed the type definitions, you can import them in your TypeScript code:

index.ts
import * as _ from 'underscore';
import { UnderscoreStatic } from 'underscore';

declare const _: UnderscoreStatic;

// Use the _.isSymbol function as described above
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In this example, we declare a const for the Underscore library, specifying the UnderscoreStatic interface for the type. This allows us to use the _.isSymbol function as usual. The declare const line tells TypeScript that we are importing an external object, and the const keyword creates a local reference to the imported object. The UnderscoreStatic interface is defined in the Underscore.js type definitions package, and it describes the types and methods of the Underscore.js library.