隐式返回，但仅当没有块时才返回。
* 当单线扩展到多行并且程序员忘记添加时，这将导致错误return。
* 隐式返回在语法上是模棱两可的。(name) => {id: name}返回对象{id:name}…对吗？错误。它返回undefined。这些括号是一个明确的块。id:是一个标签。
我会在此添加一个块的定义：
块语句（或其他语言的复合语句）用于将零个或多个语句分组。该块由一对大括号分隔。
例子 ：
// returns: undefined// explanation: an empty block with an implicit return((name) => {})()// returns: 'Hi Jess'// explanation: no block means implicit return((name) => 'Hi ' + name)('Jess')// returns: undefined// explanation: explicit return required inside block, but is missing.((name) => {'Hi ' + name})('Jess')// returns: 'Hi Jess'// explanation: explicit return in block exists((name) => {return 'Hi ' + name})('Jess')// returns: undefined// explanation: a block containing a single label. No explicit return.// more: https://developer.mozilla.org/en-US/docs/Web/Javascript/Reference/Statements/label((name) => {id: name})('Jess')// returns: {id: 'Jess'}// explanation: implicit return of expression ( ) which evaluates to an object((name) => ({id: name}))('Jess')// returns: {id: 'Jess'}// explanation: explicit return inside block returns object((name) => {return {id: name}})('Jess')
