JavaScript如何實現(xiàn)購物車結(jié)算

這篇文章主要介紹JavaScript如何實現(xiàn)購物車結(jié)算，文中介紹的非常詳細，具有一定的參考價值，感興趣的小伙伴們一定要看完！

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(fù)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(fù)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(fù)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(fù)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(fù)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(fù)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(fù)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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