查找布尔值的总和 JavaScript 对象数组

Question

Hi i am trying to find the sum of Boolean values in the object array in JavaScript

My json like be

var myoBj = [{
  "id": 1,
  "day": 1,
  "status": true
}, {
  "id": 2,
  "day": 1,
  "status": false
}, {
  "id": 3,
  "day": 1,
  "status": false
}, {
  "id": 4,
  "day": 3,
  "status": false
}];

i want the sum of all status values using reduce function in JavaScript/ typescript

i want to show overall status as true only when all status are true else it should be false

Answer 1

var result = myObj.reduce((sum, next) => sum && next.status, true);

如果每个值都为真，这应该返回真。

Answer 2

If you want to sum lets say, day items value depending on the status flag, this can looks like:

var result = myObj.reduce((res, item) => item.status ? res + item.day : res, 0);

Update 1

For overall status in case of all statuses are true you should use every method:

var result = myObj.every(item => item.status);

Answer 3

You could use Array.some with predicate a => !a.status or Array.every with predicate a => a.status .

Either of them will short-circuit if you find a mismatch, while Array.reduce will not.

Answer 4

If you must use reduce you can take advantage of the fact that x*false == 0 , and so you can do the following:

 const myObj=[{id:1,day:1,status:true},{id:2,day:1,status:false},{id:3,day:1,status:false},{id:4,day:3,status:false}], res = !!myObj.reduce((bool, {status}) => bool*status, true); console.log(res);