Parsing money out of text strings in various different given formats (Craigslist postings, Facebook wall posts, etc.)

get_price_spec.js

function getPrice(str) {
  if(str.indexOf('$') !== -1) {
    // Dollar sign present - it always trumps other number values
    var reg = /\$([\d,.]+)/g;
  } else if(/(\d[\d.,]+)/.test(str)) {
    // Digits with decimals found - more likely to be price than other number values
    var reg = /(\d[\d.,]+)/g;
  } else {
    // Any numbers at all that are surrounded by spaces (fallback; worst accuracy)
    var reg = /\s+([\d]+)\s+/g;
  }

  var prices =[];
  var price;
  // Match padded string so we can always expect spaces before and after
  while((price = reg.exec(' ' + str + ' '))!=null) {
      prices.push( parseFloat(price[1]) );
  }
  
  // Return '0' when no matches are found
  if(prices.length === 0) {
    return 0;
  }

  // Return minimum price
  var min = prices[0];
  var len = prices.length;
  for (var i = 1; i < len; i++) if (prices[i] < min) min = prices[i];

  // Return formatted as money
  return min;
}


describe('Parse money from string', function() {
  
  it('should choose number with dollar sign over any other numbers', function() {
    var msg = "5 pairs girls size 6 with adjustable waist. Easy wear on white and green pair. $8 OBO";
    var result = 8;
    expect(getPrice(msg)).toEqual(result);
  });

  it('should choose lowest number with dollar sign', function() {
    var msg = "4 child bottoms and 32 child tops paid over $40 want $15 obo";
    var result = 15;
    expect(getPrice(msg)).toEqual(result);
  });

  it('should choose lowest number with no dollar sign if no dollar signs are present', function() {
    var msg = "Top is small child bottoms are extra small child worn once paid over 40 want 20 obo";
    var result = 20;
    expect(getPrice(msg)).toEqual(result);
  });

  it('should return 0 with no price or number surrounded by spaces', function() {
    var msg = "Looking for boys 2t shirts old navy or children's place new or gently used please ! Thank u";
    var result = 0;
    expect(getPrice(msg)).toEqual(result);
  });

  it('should choose number with decimal point over any other numbers', function() {
    var msg = "New only used a few times asking 40.00 OBO text me 4133612";
    var result = 40;
    expect(getPrice(msg)).toEqual(result);
  });

  it('should choose lowest number with decimal point over any other lower numbers', function() {
    var msg = "Boys size 5 shirts asking 12.00";
    var result = 12;
    expect(getPrice(msg)).toEqual(result);
  });

  it('should choose lowest number when no dollar sign and no decimal point numbers are present', function() {
    var msg = "Boys size 5t shirts for 7";
    var result = 7;
    expect(getPrice(msg)).toEqual(result);
  });

  it('should return 0 when the text "free" is present with no prices', function() {
    var msg = "i have a stack of parents magaze, for FREE if anyone wants them";
    var result = 0;
    expect(getPrice(msg)).toEqual(result);
  });
});