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

The once function in the Underscore library is a higher-order function that takes in a function and returns a new version of that function that can only be called once. Here's an example of how to use it:

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

function sayHello() {
  console.log('Hello!');
}

const sayHelloOnce = _.once(sayHello);

sayHelloOnce(); // logs 'Hello!'
sayHelloOnce(); // does nothing
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In the example above, we first import the Underscore library using require. We then define a sayHello function that logs 'Hello!' to the console.

We then pass sayHello to the _.once function to create a new function sayHelloOnce that can only be called once.

When we call sayHelloOnce for the first time, it logs 'Hello!' to the console. When we call it for the second time, nothing happens since the function has already been called once and is now effectively "used up".