JS實現簡易計算器
阿新 • • 發佈：2020-02-15
用JS實現簡易計算器，供大家參考，具體內容如下
首先建立結構和樣式
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width,initial-scale=1.0">
<title>Document</title>
<style>
body{
margin:0;
padding:0;
background-color: #abcdef;
}
.cal{
width:560px;
height:100px;
margin:0 auto;
padding-top:300px;
}
</style>
</head>
<body>
<div class="cal">
<p>
<input type="text" class="num1" value="1">
<span class="sign">+</span>
<input type="text" class="num2" value="1">
<span>=</span>
<span class="res">2</span>
</p>
<p>
<input type="button" value="+">
<input type="button" value="-">
<input type="button" value="*">
<input type="button" value="/">
</p>
</div>
<script>
</script>
</body>
</html>然後新增Java script
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width,initial-scale=1.0">
<title>Document</title>
<style>
body{
margin:0;
padding:0;
background-color: #abcdef;
}
.cal{
width:560px;
height:100px;
margin:0 auto;
padding-top:300px;
}
</style>
</head>
<body>
<div class="cal">
<p>
<input type="text" class="num1" value="1">
<span class="sign">+</span>
<input type="text" class="num2" value="1">
<span>=</span>
<span class="res">2</span>
</p>
<p>
<input type="button" value="+" class="btn">
<input type="button" value="-" class="btn">
<input type="button" value="*" class="btn">
<input type="button" value="/" class="btn">
</p>
</div>
<script>
var cal=document.querySelector(".cal");
var num1=cal.querySelector(".num1");
var num2=cal.querySelector(".num2");
var sign=cal.querySelector(".sign");
var res=cal.querySelector(".res");
var btns=cal.querySelectorAll(".btn");
btns[0].onclick=add;
btns[1].onclick=subtract;
btns[2].onclick=multiply;
btns[3].onclick=divide;
function add(){
sign.innerHTML="+";
//由於DOM獲取到的值都是字串形式，因此進行操作時需要先轉為number型別
res.innerHTML=Number(num1.value)+Number(num2.value);
}
function subtract(){
sign.innerHTML="-";
res.innerHTML=Number(num1.value)-Number(num2.value);
}
function multiply(){
sign.innerHTML="*";
res.innerHTML=Number(num1.value)*Number(num2.value);
}
function divide(){
sign.innerHTML="/";
res.innerHTML=Number(num1.value)/Number(num2.value);
}
</script>
</body>
</html>程式碼的優化：
迴圈實現繫結
給一個外部介面，用於新增運算
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width,initial-scale=1.0">
<title>Document</title>
<style>
body{
margin:0;
padding:0;
background-color: #abcdef;
}
.cal{
width:560px;
height:100px;
margin:0 auto;
padding-top:300px;
}
</style>
</head>
<body>
<div class="cal">
<p>
<input type="text" class="num1" value="1">
<span class="sign">+</span>
<input type="text" class="num2" value="1">
<span>=</span>
<span class="res">2</span>
</p>
<p>
<input type="button" value="+" class="btn" title="add">
<input type="button" value="-" class="btn" title="subtract">
<input type="button" value="*" class="btn" title="multiply">
<input type="button" value="/" class="btn" title="divide">
<input type="button" value="%" class="btn" title="mod">
</p>
</div>
<script>
var cal=document.querySelector(".cal");
var num1=cal.querySelector(".num1");
var num2=cal.querySelector(".num2");
var sign=cal.querySelector(".sign");
var res=cal.querySelector(".res");
var btns=cal.querySelectorAll(".btn");
//給每個按鈕繫結事件
for(var i=0;i<btns.length;i++){
operate(i);
}
//運算函式
function operate(i){
var op=btns[i].value;//獲取運算
var opName=btns[i].title;//獲取運算名
//繫結事件
btns[i].onclick=function(){
sign.innerHTML=op;
res.innerHTML=operation[opName](Number(num1.value),Number(num2.value));
}
}
var operation={
add:function(n1,n2){
return n1+n2;
},subtract:function(n1,n2){
return n1-n2;
},multiply:function(n1,n2){
return n1*n2;
},divide:function(n1,n2){
return n1/n2;
},//給一個新增運算的介面
addOperation:function(name,fn){
//如果該運算不存在
if(!this.name){
this[name]=fn;
}
}
}
//新增取餘運算
operation.addOperation("mod",function(n1,n2){
return n1%n2;
});
</script>
</body>
</html>這樣就圓滿完成咯
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支援我們。