[英]I want to get values key from object which is in array
我有很多天
"selectedDays": [
"Sunday",
"Tuesday",
"Wednesday"
]
这是即将到来的请求正文,现在我必须 map 并生成它的数量,所以我有一个 object
const Week_mapping = {
"Sunday": 0,
"Monday": 1,
"Tuesday":2,
"wednesday":3,
"Thursday": 4,
"Friday": 5,
"Saturday": 6
}
示例 1 - 假设数组有星期日、星期二、星期三。
所需的 Output:
[0,2,3]
示例 2 - 假设数组有星期日、星期一、星期二、星期三、星期五
所需的 Output:
[0,1,2,3,5]
我怎样才能做到这一点?
您可以使用简单的maps()
执行以下操作 -
const Week_mapping = { "Sunday": 0, "Monday": 1, "Tuesday": 2, "Wednesday": 3, "Thursday": 4, "Friday": 5, "Saturday": 6 } const selectedDays = [ "Sunday", "Tuesday", "Wednesday" ] // The following line will return array in which the elements in // selectedDays list will be mapped to their corresponding Week_mapping const res = selectedDays.map(element => Week_mapping[element]) console.log(res)
如果您还不了解地图,可以在此处阅读有关地图的更多信息。 基本上, map()
采用 function 并将数组的每个元素(使用 map)映射到 function 返回的结果。
所以,上面的代码也可以这样写=>
const Week_mapping = { "Sunday": 0, "Monday": 1, "Tuesday": 2, "Wednesday": 3, "Thursday": 4, "Friday": 5, "Saturday": 6 } const selectedDays = [ "Sunday", "Tuesday", "Wednesday" ] // The following function will take a week day and return the number corresponding to it function weekDaysToNumMappings (weekDay){ return Week_mapping[weekDay]; } // Now, we map each element from selectedDays to value returned by above function const res = selectedDays.map(weekDaysToNumMappings) console.log(res)
希望这可以帮助 !
这将检查是否没有选择日期:
let answer = selectedDays && selectedDays.length ?
selectedDays.map(key => Week_mapping[key])
: []
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