Coffeescript - 减少存在和非相同的代码行？

Question

在Coffeescript中，这些if和unless语句可以成为一行代码吗？

# ensure both variables are present
if var1 and var2
    # ensure the variables are different
    unless var1 is var2
        # now do something!

我需要两个变量都存在，两者都不同。

Answer 1

只需在第一个a is b中添加if的补充，Javascript将开始评估左边的表达式（短路），它不会测试a isnt b，除非他们都定义了

# Your example boils down to this
if a and b and a isnt b
     # Do something

# Why not Use a? to check if a is defined
if a? and b? and a isnt b
     # Do something