javascript腳本驗證問題？

var jiner = document.getElementById('jiner').value;

var cunqi = document.getElementById('cunqi').value;

jiner = Number(jiner);

cunqi = Number(cunqi);

var liv = 0.036; //設置利率

var r = 12;

if(!isNaN(jiner)){

alert('金額必須為數字');

return false;

}

if(!isNaN(cunqi)){

alert('存期必須為數字');

return false;

}

alert(”金額“+jiner+"存期“+cunqi+”利息為："+jiner*liv/r*cunqi)

}

check();