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

The _.sortedIndex(list, value, [iteratee], [context]) function from the Underscore library in JavaScript can be used to determine the index at which a given element should be inserted into a sorted array.

Here's an example of how to use the _.sortedIndex function:

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

const numbers = [10, 20, 30, 40, 50];

// Get the index at which to insert the value 35
const index = _.sortedIndex(numbers, 35);

console.log(index); // Output: 3
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In this example, we pass the array numbers and the value 35 to the _.sortedIndex function. The function returns the index 3, which is the index at which the value 35 should be inserted into the sorted numbers array.

Optionally, you can pass an iteratee function to the _.sortedIndex function to transform values before they are compared:

index.tsx
const users = [
  { name: 'John', age: 25 },
  { name: 'Jane', age: 28 },
  { name: 'Bob', age: 30 },
];

// Get the index at which to insert a user with age 27
const index = _.sortedIndex(users, { age: 27 }, user => user.age);

console.log(index); // Output: 1
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In this example, we pass an array of users and an object { age: 27 } to the _.sortedIndex function. We also pass an iteratee function that returns the value of the age property of each user. The function returns the index 1, which is the index at which the user object should be inserted into the sorted users array based on their age property.