JS 非标准功能
Expression closures
Obsolete since Gecko 60
The expression closure syntax is a shorthand for writing simple function.
Legacy generator function
Obsolete since Gecko 58
The function keyword can be used to define a legacy generator function inside an expression. To make the function a legacy generator, the function body should contains at least one yield expression.
[for (x of y) x]
Obsolete since Gecko 58
Array comprehensions.
(for (x of y) y)
Obsolete since Gecko 58
Generator comprehensions.
closures 表达式闭包 legacy_generator_function 旧式生成器函数 array 数组推导语法 generator 生成器推导语法