用JavaScript实现简单的乘法计算

function multiplication() {
var a = document.getElementById('input1').value;
var b = document.getElementById('input2').value;
var c = a*b;
var settings = document.getElementById('input3');
// 判断乘数a和b是否为空或者输入非数字值
if ((a=="" || isNaN(a)) || (b=="" || isNaN(b))) {
settings.value = null;
alert("输入数据有误，请重新输入！")
}
else {
settings.value = c;
}
}

计算：
<input id="input1" > × <input id="input2">
<button id="button2" onclick="multiplication()">=</button>
<input id="input3">