var var1 = ["2", "a", "2017/07/11", "", undefined, null]; for(var a = 0; a < var1.length; a++) { var toInt = parseInt(var1[a]); console.log(toInt); } console.log("\n"); for(var a = 0; a < var1.length; a++) { console.log(isInteger(var1[a])); } function isInteger(i) { return i + " is valid integer? => " + ! isNaN(parseInt(i)); }