JavaScript實現(xiàn)購物車結(jié)算的方法：1、在頁面加載后執(zhí)行function；2、獲取元素；3、設(shè)置加減按鈕；4、另存下標；5、設(shè)置加減號的點擊事件；6、創(chuàng)建復選框的狀態(tài)改變事件。

本文操作環(huán)境：windows7系統(tǒng)、javascript1.8.5版、Dell G3電腦。

JavaScript怎么實現(xiàn)購物車結(jié)算？

HTML代碼：

<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>                 小計:                 <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>                 小計:                 <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>                 小計:                 <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>                 小計:                 <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>                 小計:                 <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="">全選 </label>         <p>             商品總計:             <span id="totalCount">0</span>         </p>         <p>             商品總價:             <span id="totalPrice">0</span>         </p>     </div> </div> CSS代碼： 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代碼：

// 1.頁面加載后執(zhí)行 window.onload = function() {     // 2.獲取元素     var liCheck = document.getElementsByName("liCheck"); //li里面的復選框     var decrease = document.getElementsByClassName("decrease"); //減號     var piece = document.getElementsByClassName("piece"); //件數(shù)     var increase = document.getElementsByClassName("increase"); //加號     var price = document.getElementsByClassName("price"); //單價     var smallPrice = document.getElementsByClassName("smallPrice"); //小計     var checkAll = document.getElementById("checkAll"); //全選復選框     var totalCount = document.getElementById("totalCount"); //總計     var totalPrice = document.getElementById("totalPrice"); //總價     // 3.加減按鈕     for (var i = 0; i < decrease.length; i++) {         // 4.另存下標         decrease[i].index = i;         increase[i].index = i;         liCheck[i].index = i;         // 5.減號的點擊事件         decrease[i].onclick = function() {             // 5-1.判斷件數(shù)是否大于0             if (piece[this.index].innerHTML <= 1) {                 this.disabled = true; //當件數(shù)小于等于0時, 將減號按鈕禁用             }             // 5-1-1.當前件數(shù)-1             piece[this.index].innerHTML--;             // 5-1-2.計算小計             smallPrice[this.index].value = Number(smallPrice[this.index].value) - Number(price[this.index].innerHTML);             // 6-4.如果當前條目是被選中狀態(tài), 則需要將該商品計入總計和總價             if (liCheck[this.index].checked) { //選中                 totalCount.innerHTML--;                 totalPrice.innerHTML = Number(totalPrice.innerHTML) - Number(price[this.index].innerHTML);             }         }         // 6.加號的點擊事件         increase[i].onclick = function() {             // 6-1.將對應(yīng)的減號解禁             decrease[this.index].disabled = false;             // 6-2.當前件數(shù)+1             piece[this.index].innerHTML++;             // 6-3.計算小計             smallPrice[this.index].value = Number(smallPrice[this.index].value) + Number(price[this.index].innerHTML);             // 6-4.如果當前條目是被選中狀態(tài), 則需要將該商品計入總計和總價             if (liCheck[this.index].checked) { //選中                 totalCount.innerHTML++;                 totalPrice.innerHTML = Number(totalPrice.innerHTML) + Number(price[this.index].innerHTML);             }         }         // 7.復選框的狀態(tài)改變事件         var count = 0; //存儲選中個數(shù)         liCheck[i].onchange = function() {             // 7-1.判斷是否選中             if (this.checked) { //選中狀態(tài)                 count++;                 totalCount.innerHTML = Number(totalCount.innerHTML) + Number(piece[this.index].innerHTML); //總計加當前件數(shù)                 totalPrice.innerHTML = Number(totalPrice.innerHTML) + Number(smallPrice[this.index].value); //總計加當前件數(shù)                 // 7-1-1. 判斷選中個數(shù)是否與復選框個數(shù)一致             } else { //取消選中狀態(tài)                 count--;                 totalCount.innerHTML = Number(totalCount.innerHTML) - Number(piece[this.index].innerHTML); //總計加當前件數(shù)                 totalPrice.innerHTML = Number(totalPrice.innerHTML) - Number(smallPrice[this.index].value); //總計加當前件數(shù)             }             count == liCheck.length ? checkAll.checked = true : checkAll.checked = false;         }     }     // 8.全選復選框     checkAll.onchange = function() {         totalCount.innerHTML = 0; //總計置為0         totalPrice.innerHTML = 0; //總價置為0         for (var j = 0; j < liCheck.length; j++) {             // 8-1. 將li里面的復選框與全選狀態(tài)保持一致             liCheck[j].checked = this.checked;             // 8-2. 判斷是否全選             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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