var x = [12341, 12342, 12345, 'sdfdf', 3123, 12346, 12345.42, 12349428];
var f = x.filter(function(v){return v%1===0&&(v>=12340000&&v<=12349999)});
// f: Array [ 12349428 ]
var x = [12341, 12342, 12345, 'sdfdf', 3123, 12346, 12345.42];
var f = x.filter(function(v){return v%1===0&&(v>=12340&&v<=12349)});
// Output: Array [ 12341, 12342, 12345, 12346 ]