how to use the isfunction function from the underscore library in javascript

To use the isFunction function from the underscore library in JavaScript, you must first include the library in your project. You can do this by either downloading the library and linking to it in your HTML file, or by using a package manager such as npm or yarn. After including the library, you can use the isFunction function to check if a given value is a function or not.

Here's an example:

index.tsx
// import underscore library
const _ = require('underscore');

// define a function
function add(num1, num2) {
  return num1 + num2;
}

// check if variable is a function
console.log(_.isFunction(add)); // output: true

// check if variable is not a function
let num = 5;
console.log(_.isFunction(num)); // output: false
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In the example above, we import the underscore library using the require function. We define a function called add and then use the isFunction function to check if it is indeed a function. We then check if a variable num is a function, which returns false since num is a number, not a function.