为什么我的CoffeeScript if/else语句不起作用？

Question

当有人更改选择选项时,我一直在尝试更新总价.这是我正在使用的select元素:

<select id="payment_talks_purchased" name="payment[talks_purchased]">
  <option value="1">One</option>
  <option value="2">Three</option>
</select>

这是我正在使用的jQuery:

jQuery(document).ready(function() {
  var price = $(".total-price span.price")
  var save = $(".savings")
  $("#payment_talks_purchased").change(function() {
    var selection = $("#payment_talks_purchased").val()
    if (selection == 2) {
      price.html("$12");
      save.css("visibility", "visible");
    } else if (selection == 1) {
      price.html("$5");
      save.css("visibility", "hidden");
    }
  });  
});

它完美地运作.它将价格更改为12美元并显示折扣消息.如果我将选择选项更改回One/1,它会将文本更改回$ 5并删除折扣消息.

我将其转换为CoffeeScript,但它只在我进行第一次更改时才有效.价格已更新.但是,当我尝试将其更改回选项1时,它不会更新.

jQuery ->
  price = $(".total-price span.price")
  save = $(".savings")
  select = $("#payment_talks_purchased")
  select.change ->
    selection = select.val()
    if selection = 2
      price.html "$12"
      return save.css "visibility", "visible"
    else if selection = 1
      price.html "$5"
      return save.css "visibility", "hidden"

我已经工作了好几个小时,我的智慧结束了.任何帮助将不胜感激.

Answer 1

您selection = 1的if语句内部(仍然)是CoffeeScript中的一项任务,您需要将其==用于比较.试试这个:

jQuery ->
  price = $(".total-price span.price")
  save = $(".savings")
  select = $("#payment_talks_purchased")
  select.change ->
    selection = select.val()
    if selection == '2'
      price.html "$12"
      return save.css "visibility", "visible"
    else if selection == '1'
      price.html "$5"
      return save.css "visibility", "hidden"

此外,==转换为===你将要比较字符串,除非你想使用你的价值"投射"你的数字selection = +select.val()(感谢Trevor Burnham这个演员技巧)或parseInt(select.val(), 10).

Answer 2

你可以使用开关:

switch selection
  when '2'
    price.html "$12"
    save.css "visibility", "visible"
  when '1'
    price.html "$5"
    save.css "visibility", "hidden"

你也可以带走return,因为函数总会返回它们的最终值.