compromise/src/result/subset/values/numOrdinal/index.js

natural language processing in the browser

'use strict';
const toNumber = require('../toNumber');

//turn a number like 5 into an ordinal like 5th
const numOrdinal = function(ts) {
  let num = toNumber(ts);
  if (!num && num !== 0) {
    return null;
  }
  //the teens are all 'th'
  let tens = num % 100;
  if (tens > 10 && tens < 20) {
    return '' + num + 'th';
  }
  //the rest of 'em
  const mapping = {
    0: 'th',
    1: 'st',
    2: 'nd',
    3: 'rd'
  };
  let str = '' + num;
  let last = str.slice(str.length - 1, str.length);
  if (mapping[last]) {
    str += mapping[last];
  } else {
    str += 'th';
  }
  return str;
};

module.exports = numOrdinal;