How can we display the previous value of given value while the value is given from an array and we should display the previous value of it?
var theArray = [1, 2, 3, 4, 5, 6, 7, 8, 9, 14, 15];
const findValue = (arr, input) => {
// To do
}
findValue(theArray, 15)
When we give 15 in input then the output would be 14.
Try to get the index of the input, and then get the previous index:
var theArray = [1,2,3,4,5,6,7,8,9,14,15];
const findValue = (arr, input) => arr[arr.indexOf(input) - 1]
console.log(findValue(theArray , 15))
You should consider the case where input is at the index 0...
const findValue = (arr, input) => {
let previousItemIndex = arr.findIndex(e => e === input) - 1;
return previousItemIndex < 0 ? null : arr[previousItemIndex];
}
This will return null if there isn't any previous item and will find from left to right.
If it is assumed that the given value is unique, you can just search the array for the value you are looking for (probably using a known search algorithm e.g., binary search) and then return the previous index (if it is not the first item of course).
1? please add your code, you tried.