Get the rank of an array of numbers

This function returns an array with the same length as the input array, where each element is the rank of the corresponding element in the input array.

JavaScript:

let rankArray = arr => arr.slice().sort((a, b) => a - b).map((v, i, sortedArr) => sortedArr.indexOf(arr[i]) + 1);

// Example
console.log(rankArray([40, 20, 10, 30])); // [4, 2, 1, 3]
console.log(rankArray([1.2, 0.5, 1.1, 0.9])); // [4, 1, 3, 2]

TypeScript:

let rankArray = (arr: number[]): number[] => arr.slice().sort((a, b) => a - b).map((v, i, sortedArr) => sortedArr.indexOf(arr[i]) + 1);

// Example
console.log(rankArray([40, 20, 10, 30])); // [4, 2, 1, 3]
console.log(rankArray([1.2, 0.5, 1.1, 0.9])); // [4, 1, 3, 2]