number-abbreviate/index.js

Abbreviate a number and add unit letters e.g. 2200000 => '2.2m'

(function(root){
  'use strict';

  function NumberAbbreviate() {
    var units
    if (!(this instanceof NumberAbbreviate)) {
      // function usage: abbrev(n, decPlaces, units)
      var n = arguments[0]
      var decPlaces = arguments[1]
      units = arguments[2]
      var ab = new NumberAbbreviate(units)
      return ab.abbreviate(n, decPlaces)
    }
    // class usage: new NumberAbbreviate(units)
    units = arguments[0]
    this.units = units == null ? ['k', 'm', 'b', 't'] : units
  }

  NumberAbbreviate.prototype._abbreviate = function(number, decPlaces) {
    decPlaces = Math.pow(10, decPlaces)

    for (var i = this.units.length - 1; i >= 0; i--) {

      var size = Math.pow(10, (i + 1) * 3)

      if (size <= number) {
        number = Math.round(number * decPlaces / size) / decPlaces

        if ((number === 1000) && (i < this.units.length - 1)) {
          number = 1
          i++
        }

        number += this.units[i]

        break
      }
    }

    return number
  }

  NumberAbbreviate.prototype.abbreviate = function(number, decPlaces) {
    var isNegative = number < 0
    var abbreviatedNumber = this._abbreviate(Math.abs(number), decPlaces || 0)

    return isNegative ? '-' + abbreviatedNumber : abbreviatedNumber;
  }

  if (typeof module !== 'undefined' && module.exports) {
    module.exports = NumberAbbreviate
  } else {
    root.NumberAbbreviate = NumberAbbreviate
  }

})(this);