walrusWeight.js

var input = [4, 900, 500, 498, 4];
function walrusWeight(input) {
 var target = 1000;
  var optimum = 0;
  var sums = [];
  sums.push(optimum);
  
  for(var i=0; i < input.length; i++) {
    var newSums = [];
    for(var j=0; j < sums.length; j++) {
      var newSum = sums[j] + input[i];
      if (newSum <= target) {
        newSums.push(newSum);
        if (newSum > optimum) {
          optimum = newSum;
        }
      } else if ((Math.abs(target-newSum) < Math.abs(target-optimum)) || (Math.abs(target-newSum) == Math.abs(target-optimum) && newSum > optimum)) {
        optimum = newSum;
      }
    }
    sums = sums.concat(newSums);
  }
  return optimum;
}

walrusWeight(input);