WEB部分
<!DOCTYPE html>
<html>
<body>
<from>
第一个数字:<br>
<input type="text" id="num1">
<br>
第二个数字:<br>
<input type="text"id="num2">
<br>
运算结果:<br>
<p id="result">结果将在这里显示</p>
</from>
<button id="add">+</button>
<button id="subtract">-</button>
<button id="multiply">×</button>
<button id="divide">÷</button>
</body>
</html>
JavaScript
// 获取按钮
var addBtn = document.getElementById('add');
var subtractBtn = document.getElementById('subtract');
var multiplyBtn = document.getElementById('multiply');
var divideBtn = document.getElementById('divide');
var resultNum = document.getElementById('result');
// 定义全局变量
var a_int;
var b_int;
// 为按钮添加点击方法
addBtn.onclick = function(){
getInputNum();
var result = addition(a_int, b_int);
resultNum.innerHTML = String(result);
};
subtractBtn.onclick = function(){
getInputNum();
var result = subtraction(a_int, b_int);
resultNum.innerHTML = String(result);
};
multiplyBtn.onclick = function(){
getInputNum();
var result = multiplication(a_int, b_int);
resultNum.innerHTML = String(result);
};
divideBtn.onclick = function(){
getInputNum();
var result = division(a_int, b_int);
resultNum.innerHTML = String(result);
};
// 获取 input 的值转为数字
function getInputNum(){
// 这里是局部变量
var a = document.getElementById('num1').value;
var b = document.getElementById('num2').value;
// 将转化后的数字赋值给全局变量
a_int = parseInt(a, 10);
b_int = parseInt(b, 10);
}
// 加减乘除
function addition(x, y){
return x + y;
}
function subtraction(x, y){
return x - y;
}
function multiplication(x, y){
return x * y;
}
function division(x, y){
if (y == 0){
alert('0不能做除数');
return;
}
else{
return x / y;
}
}