Package on npm: probability-to-friendly-string. Requires ES6, can be used with or without node.js.

Usage:

// This line isn't needed if you're not using through npm
import FriendlyProbability from 'probability-to-friendly-string';
let friendly = FriendlyProbability.fromProbability(.723);

friendly is a class of type FriendlyProbability that has properties

• friendlyString: a string representing the probability (in this case "5 in 7")
• friendlyDescription: a qualitative description of the probability ("Still possible", "Flip a coin", "Good chance", etc.)
• numerator: the numerator of the probability (in this case 5)
• denominator: the denominator of the probability (in this case 7)

Note that passing a value less than 0 or greater than 1 to FriendlyProbability.fromProbability() will throw an Error.