JavaScript实现购物车结算的方法：1、在页面加载后执行function；2、获取元素；3、设置加减按钮；4、另存下标；5、设置加减号的点击事件；6、创建复选框的状态改变事件。
本文操作环境：windows7系统、javascript1.8.5版、Dell G3电脑。
JavaScript怎么实现购物车结算？
<div id=container>
<ul>
<li>
<input type=checkBox name=liCheck id= value=>
<button type=button class=decrease disabled=disabled>-</button>
<p>
<span class=piece>0</span>件
</p>
<button type=button class=increase>+</button>
<p>
<span class=price>10</span>元
</p>
<p>
小计:
<input class=smallPrice type=text name= id= value=0 disabled=disabled>
</p>
</li>
<li>
<input type=checkBox name=liCheck id= value=>
<button type=button class=decrease disabled=disabled>-</button>
<p>
<span class=piece>0</span>件
</p>
<button type=button class=increase>+</button>
<p>
<span class=price>20</span>元
</p>
<p>
小计:
<input class=smallPrice type=text name= id= value=0 disabled=disabled>
</p>
</li>
<li>
<input type=checkBox name=liCheck id= value=>
<button type=button class=decrease disabled=disabled>-</button>
<p>
<span class=piece>0</span>件
</p>
<button type=button class=increase>+</button>
<p>
<span class=price>30</span>元
</p>
<p>
小计:
<input class=smallPrice type=text name= id= value=0 disabled=disabled>
</p>
</li>
<li>
<input type=checkBox name=liCheck id= value=>
<button type=button class=decrease disabled=disabled>-</button>
<p>
<span class=piece>0</span>件
</p>
<button type=button class=increase>+</button>
<p>
<span class=price>40</span>元
</p>
<p>
小计:
<input class=smallPrice type=text name= id= value=0 disabled=disabled>
</p>
</li>
<li>
<input type=checkBox name=liCheck id= value=>
<button type=button class=decrease disabled=disabled>-</button>
<p>
<span class=piece>0</span>件
</p>
<button type=button class=increase>+</button>
<p>
<span class=price>50</span>元
</p>
<p>
小计:
<input class=smallPrice type=text name= id= value=0 disabled=disabled>
</p>
</li>
</ul>
<div class=sum>
<label>
<input type=checkBox name= id=checkAll value=>全选
</label>
<p>
商品总计:
<span id=totalCount>0</span>
</p>
<p>
商品总价:
<span id=totalPrice>0</span>
</p>
</div>
</div>
CSS代码：
html,body,ul,p {
margin:0;
padding:0;
}
ul,li {
list-style:none;
}
ul {
width:450px;
}
li {
display:flex;
justify-content:space-around;
}
.sum {
width:450px;
display:flex;
justify-content:space-around;
}
#container {
width:450px;
margin:100px auto;
}JS代码：
// 1.页面加载后执行 window.onload = function() { // 2.获取元素 var liCheck = document.getElementsByName(liCheck); //li里面的复选框 var decrease = document.getElementsByClassName(decrease); //减号 var piece = document.getElementsByClassName(piece); //件数 var increase = document.getElementsByClassName(increase); //加号 var price = document.getElementsByClassName(price); //单价 var smallPrice = document.getElementsByClassName(smallPrice); //小计 var checkAll = document.getElementById(checkAll); //全选复选框 var totalCount = document.getElementById(totalCount); //总计 var totalPrice = document.getElementById(totalPrice); //总价 // 3.加减按钮 for (var i = 0; i < decrease.length; i++) { // 4.另存下标 decrease[i].index = i; increase[i].index = i; liCheck[i].index = i; // 5.减号的点击事件 decrease[i].onclick = function() { // 5-1.判断件数是否大于0 if (piece[this.index].innerHTML <= 1) { this.disabled = true; //当件数小于等于0时, 将减号按钮禁用 } // 5-1-1.当前件数-1 piece[this.index].innerHTML--; // 5-1-2.计算小计 smallPrice[this.index].value = Number(smallPrice[this.index].value) - Number(price[this.index].innerHTML); // 6-4.如果当前条目是被选中状态, 则需要将该商品计入总计和总价 if (liCheck[this.index].checked) { //选中 totalCount.innerHTML--; totalPrice.innerHTML = Number(totalPrice.innerHTML) - Number(price[this.index].innerHTML); } } // 6.加号的点击事件 increase[i].onclick = function() { // 6-1.将对应的减号解禁 decrease[this.index].disabled = false; // 6-2.当前件数+1 piece[this.index].innerHTML++; // 6-3.计算小计 smallPrice[this.index].value = Number(smallPrice[this.index].value) + Number(price[this.index].innerHTML); // 6-4.如果当前条目是被选中状态, 则需要将该商品计入总计和总价 if (liCheck[this.index].checked) { //选中 totalCount.innerHTML++; totalPrice.innerHTML = Number(totalPrice.innerHTML) + Number(price[this.index].innerHTML); } } // 7.复选框的状态改变事件 var count = 0; //存储选中个数 liCheck[i].onchange = function() { // 7-1.判断是否选中 if (this.checked) { //选中状态 count++; totalCount.innerHTML = Number(totalCount.innerHTML) + Number(piece[this.index].innerHTML); //总计加当前件数 totalPrice.innerHTML = Number(totalPrice.innerHTML) + Number(smallPrice[this.index].value); //总计加当前件数 // 7-1-1. 判断选中个数是否与复选框个数一致 } else { //取消选中状态 count--; totalCount.innerHTML = Number(totalCount.innerHTML) - Number(piece[this.index].innerHTML); //总计加当前件数 totalPrice.innerHTML = Number(totalPrice.innerHTML) - Number(smallPrice[this.index].value); //总计加当前件数 } count == liCheck.length ? checkAll.checked = true : checkAll.checked = false; } } // 8.全选复选框 checkAll.onchange = function() { totalCount.innerHTML = 0; //总计置为0 totalPrice.innerHTML = 0; //总价置为0 for (var j = 0; j < liCheck.length; j++) { // 8-1. 将li里面的复选框与全选状态保持一致 liCheck[j].checked = this.checked; // 8-2. 判断是否全选 if (this.checked) { count = liCheck.length; totalCount.innerHTML = Number(totalCount.innerHTML) + Number(piece[j].innerHTML); totalPrice.innerHTML = Number(totalPrice.innerHTML) + Number(smallPrice[j].value); } else { count = 0; } } } }
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