Finding two non-subsequent elements in array which sum is minimal

function findMinNonAdjacentPair(a) {    var mins = [];        // quick exits:    if (a.length < 5) return {error: "no solution, too few elements."};    if (a.some(isNaN)) return {error: "non-numeric values given."};        // collect 4 smallest values by their indexes        for (var i = 1; i < a.length - 1; i++) { // O(n)        if (mins.length < 4 || a[i] < a[mins[3]]) {            // need to keep record of this element in sorted list of 4 elements            for (var j = Math.min(mins.length - 1, 2); j >= 0; j--) { // O(1)                if (a[i] >= a[mins[j]]) break;                mins[j+1] = mins[j];            }            mins[j+1] = i;        }    }    // mins now has the indexes to the 4 smallest values    // Find the smallest sum    var result = {        sum: a[mins[mins.length-1]]*2+1 // large enough    }        for (var j = 0; j < mins.length-1; j++) { // O(1)        for (var k = j + 1; k < mins.length; k++) {            if (Math.abs(mins[j] - mins[k]) > 1) { // not adjacent                if (result.sum    > a[mins[j]]+a[mins[k]]) {                    result.sum    = a[mins[j]]+a[mins[k]];                    result.index1 = mins[j];                    result.index2 = mins[k];                };                if (k < j + 3) return result; // cannot be improved                break; // exit inner loop: it cannot bring improvement            }        }    }    return result;}// Get I/O elementsvar input = document.getElementById('in');var output = document.getElementById('out');var select = document.getElementById('pre');function process() {    // translate input to array of numbers    var a = input.value.split(',').map(Number);    // call main function and display returned value    output.textContent = JSON.stringify(findMinNonAdjacentPair(a), null, 4);}// respond to selection from listselect.onchange = function() {    input.value = select.value;    process();}// respond to change in input boxinput.oninput = process;// and produce result upon load:process();

Type comma-separated list of values (or select one):</br><input id="in" value="2, 2, 1, 2, 4, 2, 6"> <=<select id="pre">    <option value="5, 2, 4, 6, 3, 7">5, 2, 4, 6, 3, 7</option>    <option value="1, 2, 3, 3, 2, 1">1, 2, 3, 3, 2, 1</option>    <option value="4, 2, 1, 2, 4">4, 2, 1, 2, 4</option>    <option value="2, 2, 1, 2, 4, 2, 6" selected>2, 2, 1, 2, 4, 2, 6</option></select></br>Output:</br><pre id="out"></pre>