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

To use the isNumber function from the Underscore library in TypeScript, you need to first install the Underscore library and its type definitions:

index.ts
npm install underscore
npm install @types/underscore
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Then, you can import the isNumber function and use it in your TypeScript code as follows:

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

let value: any = 123;
if (_.isNumber(value)) {
  console.log('value is a number');
} else {
  console.log('value is not a number');
}
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In the above code, we first import the Underscore library using the import statement. We then declare a variable value of type any which can hold any type of value. We pass this variable to the isNumber function of the Underscore library using the _ object. The isNumber function returns true if the value is a number, else it returns false. Based on the return value, we print out whether the value is a number or not.

Note that we are using type annotations to specify the type of the value variable as any. If you know the type of the value beforehand, you can specify it explicitly. This can help catch errors at compile-time.

index.ts
let value: number = 123;
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