Crezzer7 Crezzer7 - 2 months ago 6
Javascript Question

check date against an array of dates

I am trying to write a function that returns a TRUE or FALSE value based on whether the date is present in the array or not. Currently I have this:

function isInArray(value, array) {
var a = array.indexOf(value) > -1;

if (a == false) {
return false; //DATE DOES NOT EXIST
}
else {
return true; //DATE EXISTS IN ARRAY
}
}


Now normally I would use a for loop, however I am generating a list of dates between a start date and end date with this while loop:

while (day > 0) {
var tDate = new Date(sDate.addDays(dayCounter));
datesArray.push(tDate);
day = day - 1; //DEDUCT THE DAYS AS ADDED

var dateExists = isInArray(value, array);
if (dateExists == false) {

}
else {
matchedDays++;
}
daysCounter++;
}


this however is not working and always returns FALSE, what do I need to do to make this work and return the correct value?

sample data:
ARRAY[26/12/2016, 27/12/2016, 28/12/2016, 29/12/2016]


value passed in
[27/12/2016]



  • return TRUE if the value exists in the array

  • return FALSE if the value does not exist in the array



probably a simple mistake above! so thankyou for any help on this. also will a time affect the date when its being checked?

Answer

You can try using the find() method (if ecmascript is supported):

Case: array contains strings

var array = ["26/12/2016", "27/12/2016", "28/12/2016", "29/12/2016"];
var value1 = "26/12/2016";  //exists
var value2 = "26/12/2026";  //doesn't exist

function isInArray(array, value) {
  return (array.find(item => {return item == value}) || []).length > 0;
}

console.log(isInArray(array, value1));
console.log(isInArray(array, value2));


Case: array contains Date objects

var array = [new Date("December 26, 2016 00:00:00"), new Date("December 27, 2016 00:00:00"), new Date("December 28, 2016 00:00:00"), new Date("December 29, 2016 00:00:00")];
var value1 = new Date("December 26, 2016 00:00:00");  //exists
var value2 = new Date("December 16, 2026 00:00:00");  //doesn't exist


function isInArray(array, value) {
  return !!array.find(item => {return item.getTime() == value.getTime()});
}

console.log(isInArray(array, value1));
console.log(isInArray(array, value2));