I have the following function:

(function(){
    function closest (num, arr) {
        var curr = arr[0];
        var diff = Math.abs (num - curr);
        for (var val = 0; val < arr.length; val++) {
            var newdiff = Math.abs (num - arr[val]);
            if (newdiff < diff) {
                diff = newdiff;
                curr = arr[val];
            }
        }
        return curr;
    }
    var _array = [2, 42, 82, 122, 162, 202, 242, 282, 322, 362],
        _number = 155;

    return closest (_number, _array);
})()

Result is 162

---

In this array I want to show the closest index to the result! The result should be number 4

I have the following function:

(function(){
    function closest (num, arr) {
        var curr = arr[0];
        var diff = Math.abs (num - curr);
        for (var val = 0; val < arr.length; val++) {
            var newdiff = Math.abs (num - arr[val]);
            if (newdiff < diff) {
                diff = newdiff;
                curr = arr[val];
            }
        }
        return curr;
    }
    var _array = [2, 42, 82, 122, 162, 202, 242, 282, 322, 362],
        _number = 155;

    return closest (_number, _array);
})()

Result is 162

---

In this array I want to show the closest index to the result! The result should be number 4

• javascript
• arrays
• indexing
• find
• closest

Share Improve this question Follow edited Oct 6, 2022 at 8:05 EugenSunic 13.7k1515 gold badges6666 silver badges9595 bronze badges asked Feb 2, 2020 at 17:48 bakhshibakhshi 3311 silver badge44 bronze badges 0

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2 Answers 2

Sorted by: Reset to default 3

Here is a more straightforward solution (not optimal):

1. find the difference between the number and the numbers in the array
2. find the minimum in the new array of differences
3. Now find the index of that minimum

var _array = [2, 42, 82, 122, 162, 202, 242, 282, 322, 362],
  _number = 155;

// closest index?

const diffArr = _array.map(x => Math.abs(_number - x));
const minNumber = Math.min(...diffArr);
const index = diffArr.findIndex(x => x === minNumber);

console.log('Result index', index);

You could store the index and return this value.

function closest(num, arr) {
    var curr = arr[0],
        diff = Math.abs(num - curr),
        index = 0;

    for (var val = 0; val < arr.length; val++) {
        let newdiff = Math.abs(num - arr[val]);
        if (newdiff < diff) {
            diff = newdiff;
            curr = arr[val];
            index = val;
        }
    }
    return index;
}

var array = [2, 42, 82, 122, 162, 202, 242, 282, 322, 362],
    number = 155;

console.log(closest(number, array));