[英]How can I fix ES6 Eslint errors while trying to return a ternary operator in arrow function?
I understand that () => {}
does not need return, however if it is not there then Eslint
complains about unused expressions. 我知道
() => {}
不需要返回,但如果不存在则Eslint
抱怨未使用的表达式。
export const isInInterval = (from, to, target) => {
if (isNaN(Date.parse(to)) && isNaN(Date.parse(from)) === true) {
return
}
const toUnixTimestamp = time => new Date(time).getTime()
toUnixTimestamp(to) - target > toUnixTimestamp(from) ? true : false
}
Here is the function: it tries to find out whether some specified date( to
) minus specified period( target
) is later in time than from
. 下面是函数:它试图找出一些指定日期(是否
to
)减去指定时间内( target
)后是在时间上比from
。 It should return true if so and false in the opposite case. 如果是这样,它应该返回true而在相反的情况下应该返回false。 I keep bumping into eslint error
expected assignment to a function call and instead saw expression
. 我不断碰到eslint错误,
expected assignment to a function call and instead saw expression
。
I tried to rewrite it several times, but in most iterations I got `arrow function expects no return error, ex.: 我尝试多次重写它,但在大多数迭代中我得到`箭头函数期望没有返回错误,例如:
return (toUnixTimestamp(to) - target > toUnixTimestamp(from)) ? return(toUnixTimestamp(to) - target> toUnixTimestamp(from))? true : false
真假
I understand that () => {} does not need return
我明白()=> {}不需要返回
That's not the case. 事实并非如此。 Arrow functions only implicitly return when what followed the
=>
is a single expression . 当
=>
后面的内容是单个表达式时,箭头函数仅隐式返回。 If you use => {
, the opening bracket {
indicates the start of a function block, and you do indeed need to explicitly return
at the end of the block (or wherever else you want to return
something). 如果你使用
=> {
,开括号{
表示一个功能块的开头,你确实需要在块的末尾显式return
(或者你想要return
其他地方)。
At the moment, your code isn't returning anything at all - that's what the linting error is trying to tell you - the true : false
is going unused at the moment, it's just an orphaned expression. 目前,你的代码根本没有返回任何东西 - 这就是linting错误试图告诉你的 -
true : false
现在没有被使用,它只是一个孤立的表达式。
So, just add the return
statement to the beginning of your conditional: 因此,只需将
return
语句添加到条件的开头:
export const isInInterval = (from, to, target) => {
if (isNaN(Date.parse(to)) && isNaN(Date.parse(from)) === true) {
return
}
const toUnixTimestamp = time => new Date(time).getTime()
return toUnixTimestamp(to) - target > toUnixTimestamp(from)
? true
: false
}
Or, because >
evaluates to a boolean
already, you might omit the conditional operator entirely: 或者,因为
>
已经评估为boolean
,您可以完全省略条件运算符:
return toUnixTimestamp(to) - target > toUnixTimestamp(from)
Here's an example of how you would write an arrow function that does use implicit return: 这里是你如何写一个箭头函数, 它使用隐式返回的例子:
export const isEarlyTimestamp = (timestamp) => (
timestamp < 4000000
? true
: false
);
try this: 试试这个:
export const isInInterval = (from, to, target) => {
if (isNaN(Date.parse(to)) && isNaN(Date.parse(from)) === true) {
return false
}
const toUnixTimestamp = time => new Date(time).getTime()
return toUnixTimestamp(to) - target > toUnixTimestamp(from);
}
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