Format and Manipulate Numbers With Numeral.js

Often it is required that numbers be displayed in a formatted way, such as adding comma separations in long numeric values, plain old numbers with decimal places, percentages, and so on. JavaScript doesn’t come with vast formatting options like most other high level languages.
I recently found out about Numeral.js, a JavaScript library for formatting and manipulating numbers. It also allows you to add local and custom formats.