How to get boolean value if any item in array of arrays is true or false?

Question

I have this array, which is user generated and changes over time:

const data = [["2020-09-14","15:00","60","Info","April Tucker","Other","yes"],
["2020-09-14","2:00","50","Text","April Tucker","Other","yes"]]

User picks a date which saves to sessionStorage (for example: 2020-11-21): sessionStorage.getItem('date')

Then I use forEach method to know if the first item of array item has the same value:

 const checkForConflicts = () => {
    mydata.forEach((element) => {
      element.includes(sessionStorage.getItem('date'))
    })
  }

If I console log that I get boolean value for all item in the array. How to return only one boolean value, true if checkForConflict returns only false values, or false value if it returned alt least one true value.

"How to return only one boolean value, true if checkForConflict returns only false values, or false value if it returned alt least one true value." - but checkForConflict doesn't return anything... — Dai
– Dai, Commented Sep 10, 2020 at 18:50
Please have a look into both Array.prototype.every and Array.prototype.some. This should enable you to pick the right tool(s). — Peter Seliger
– Peter Seliger, Commented Sep 10, 2020 at 19:52

Peter Seliger · Accepted Answer · 2020-09-10 20:18:44Z

It might be that one of either Array.prototype.every or Array.prototype.some or even both brings you the right tool at hand.

... simplified example code ...

const data = [
  ["2020-09-14","15:00","60","Info","April Tucker","Other","yes"],
  ["2020-09-14","2:00","50","Text","April Tucker","Other","yes"]
];

console.log(
  'data.every(item => item[0] === "2020-09-14") ? ',
  data.every(item => item[0] === "2020-09-14")
);
console.log(
  'data.some(item => item[0] === "2020-09-14") ? ',
  data.some(item => item[0] === "2020-09-14")
);

data.push(
  ["2020-09-15","2:00","50","Text","April Tucker","Other","yes"]
);

console.log(
  'data.every(item => item[0] === "2020-09-14") ? ',
  data.every(item => item[0] === "2020-09-14")
);
console.log(
  'data.some(item => item[0] === "2020-09-14") ? ',
  data.some(item => item[0] === "2020-09-14")
);

.as-console-wrapper { min-height: 100%!important; top: 0; }

sonEtLumiere · Accepted Answer · 2020-09-10 18:50:29Z

0

Try the some() method:

const checkForConflicts = () => {
    mydata.forEach((element) => {
      element.some(!sessionStorage.getItem('date'))
    })
  }

answered Sep 10, 2020 at 18:50

sonEtLumiere

4,6223 gold badges15 silver badges48 bronze badges

Comments

Waqas Javed · Accepted Answer · 2020-09-10 18:54:53Z

0

well you dont need use forEach and loop on the data you can just findIndex of conflicting item -1 mean their is no conflict

const checkForConflicts = () => {
    return data.findIndex((element) => {
      element.includes(sessionStorage.getItem('date'))
    }) !== -1;
  }

Most importantly you have to return value in the function.

answered Sep 10, 2020 at 18:54

Waqas Javed

4242 silver badges11 bronze badges

Comments

Mark Schultheiss · Accepted Answer · 2020-09-10 19:43:46Z

I would suggest an array of objects, if not, alter this code to look at the first element in the array of arrays. Note I substituted a local for my test to show it here in a simple manner instead of the sessionStorage

const data = [{
    date: "2020-09-14",
    time: "15:00",
    somenumber: "60",
    cheers: "Info",
    name: "April Tucker",
    "note": "Other",
    says: "yes"
  },
  {
    date: "2020-09-14",
    time: "15:00",
    somenumber: "60",
    cheers: "Info",
    name: "Fred Tucker",
    "note": "Other",
    says: "yes"
  },
  {
    date: "2020-09-13",
    time: "2:00",
    somenumber: "50",
    cheers: "Text",
    name: "April Tucker",
    "note": "Other",
    says: "yes"
  }
];
let testdate = "2020-09-14";
let testdate2 = "2020-09-19";
const checkForConflicts = (item, testme) => {
  // compare as dates to forgive formatting etc.
  return (new Date(item).getTime() === new Date(testme).getTime())
};

// I used .filter in case you need to know how many conflicts but .some() might work also
let hasConflict = !!data.filter(x => checkForConflicts(x.date, testdate)).length;
console.log(hasConflict);

let conflictCount = data.filter(x => checkForConflicts(x.date, testdate)).length;
console.log(conflictCount);

let hasConflict2 = !!data.filter(x => checkForConflicts(x.date, testdate2)).length;
console.log(hasConflict2);

Collectives™ on Stack Overflow

How to get boolean value if any item in array of arrays is true or false?

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related