JavaScript function for replaces {n} in a string with the nth following parameter.

format.js

// Replaces {n} in a string with the nth following parameter.
const format = (text, ...values) => text.replace(/{([0-9]*)}/g, (m, i) => values[i] || m)

// Example 1
console.log(format('Hello {0}! How\'s your {1}?', 'my dear', 'day been'))
// Output: Hello my dear! How's your day been?

// Example 2
const list = ['the city', 'train', 'speed', 'convenient']

console.log(format("I went to {0} by {1}.", ...list))
// Output: I went to the city by train.
console.log(format("The {2} of the {1} makes it {3}.", ...list))
// Output: The speed of the train makes it convenient.