#267 CoffeeScript Basics

May 23, 2011 | 11 minutes | Rails 3.1

CoffeeScript allows you to write JavaScript in a concise, elegant fashion. Here I convert JavaScript code to CoffeeScript in a Rails 3.1 app.

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Resources

          orders.js.coffee
        
CreditCard =
  cleanNumber: (number) -> number.replace /[- ]/g, ""
  
  validNumber: (number) ->
    total = 0
    number = @cleanNumber(number)
    for i in [(number.length-1)..0]
      n = +number[i]
      if (i+number.length) % 2 == 0
        n = if n*2 > 9 then n*2 - 9 else n*2
      total += n
    total % 10 == 0

jQuery ->
  $("#order_credit_card_number").blur ->
    if CreditCard.validNumber(@value)
      $("#credit_card_number_error").text("")
    else
      $("#credit_card_number_error").text("Invalid credit card number.")