我如何才能使此javascript多次运行？

Question

我无法使用以下javascript。问题出在“ +”和“-”符号上。对于左边的第一个框，它工作得很好，但是我无法使其与中间或右边的框一起使用。我希望中间和右边的框起作用，就像左边的第一个框一样，因此当我按“ +”时，数量将增加，而当我按“-”时，数量将减少。谢谢！

function incrementQty() {
  var value = document.querySelector('input[name="qty"]').value;
  var cardQty = document.querySelector(".cart-qty");
  value = isNaN(value) ? 1 : value;
  value++;
  document.querySelector('input[name="qty"]').value = value;
  cardQty.innerHTML = value;
  cardQty.classList.add("rotate-x");
}

function decrementQty() {
  var value = document.querySelector('input[name="qty"]').value;
  var cardQty = document.querySelector(".cart-qty");
  value = isNaN(value) ? 1 : value;
  value > 1 ? value-- : value;
  document.querySelector('input[name="qty"]').value = value;
  cardQty.innerHTML = value;
  cardQty.classList.add("rotate-x");
}

function removeAnimation(e) {
  e.target.classList.remove("rotate-x");
}

const counter = document.querySelector(".cart-qty");
counter.addEventListener("animationend", removeAnimation);

$text-color: #2a2a2a;
$bg-color: #f2eee9;
*,
*:before,
*:after {
  box-sizing: border-box;
}

@mixin clearfix {
  content: '';
  display: table;
  clear: both;
}

body {
  font-family: 'Open Sans', sans-serif;
  color: $text-color;
  display: flex;
  height: 100vh;
  align-items: center;
  font-size: 14px;
  background: $bg-color;
  background-size: cover;
}

.container {
  position: relative;
  width: 100%;
  max-width: 280px;
  margin: 0 auto;
  &:after {
    @include clearfix;
  }
}

h1 {
  display: inline-block;
  background-color: $text-color;
  color: #fff;
  font-size: 20px;
  font-weight: normal;
  text-transform: uppercase;
  padding: 4px 20px;
  float: left;
}

.item {
  background-color: #fff;
  padding: 10px;
  box-shadow: 0 1.5px 4px rgba(0, 0, 0, 0.24), 0 1.5px 6px rgba(0, 0, 0, 0.12);
  border: 1px solid #FFFEFD;
  img {
    display: block;
    margin: auto;
    padding: 20px;
    width: 180px;
  }
  h2 {
    font-size: 1.1em;
    font-weight: normal;
    display: block;
    border-bottom: 1px solid #ccc;
    margin: 10px 0 10px 0;
    padding: 0 0 5px 0;
    em {
      display: block;
      line-height: 1.6;
      font-size: .8em;
    }
  }
}

.cart-button {
  float: right;
  margin: 12px 15px 0 0;
  img {
    width: 30px;
    height: 30px;
    margin: 0 auto;
    display: block;
    color: #888;
  }
  .cart-qty {
    background: #ff5252;
    border-radius: 50%;
    color: #fff;
    display: block;
    font-size: .8em;
    line-height: 17px;
    position: absolute;
    text-align: center;
    top: 11px;
    right: 10px;
    height: 17px;
    width: 17px;
  }
}

.qty-block {
  margin-top: 20px;
}

.qty {
  float: left;
  width: 80px;
  margin-right: 10px;
  user-select: none;
}

.increment,
.decrement {
  .qty_inc_dec & {
    float: left;
    text-align: center;
    width: 30px;
    cursor: pointer;
    font-size: 1.2em;
    line-height: 20px;
    height: 25px;
    vertical-align: middle;
    background-color: #fff;
    border: 1px solid #ccc;
  }
}

.increment {
  .qty_inc_dec & {
    border-bottom: 0;
    line-height: 25px;
  }
}

.qty_inc_dec {
  float: left;
  width: 10px;
  height: 50px;
  display: inline-block;
}

input[type="text"] {
  .qty & {
    float: left;
    font-family: "Open Sans", sans-serif;
    outline: 0;
    font-size: 1.2em;
    text-align: center;
    width: 50px;
    height: 50px;
    color: $text-color;
    line-height: 40px;
    border: 1px solid #ccc;
    border-right: 0;
  }
}

button[type="button"] {
  cursor: pointer;
  width: 168px;
  border: none;
  color: $text-color;
  background: #fff;
  height: 50px;
  font-size: 1.2em;
  font-family: 'Open Sans', sans-serif;
  transition: all .2s;
  border: 1px solid #ccc;
  box-shadow: 0 1px 2px #fff;
  &:hover {
    box-shadow: 0 1px 2px #cbc3ba;
  }
  &:active,
  &:focus {
    outline: none;
  }
}

.rotate-x {
  animation-duration: .6s;
  animation-name: rotate-x;
}

@keyframes rotate-x {
  from {
    transform: rotateY(0deg);
  }
  to {
    transform: rotateY(360deg);
  }
}

<div class="container">
  <h1>Holiday <strong>Deals</strong></h1>
  <div class="cart-button">
    <img src="http://www.milanmilosev.com/external/codepen/img/cart.png" width="30" height="30">
    <span class="cart-qty">1</span> </div>
  <div class="item">
    <img src="http://www.milanmilosev.com/external/codepen/img/asus.png" alt="">
    <h2>ASUS E200HA-UB02-GD<em>Intel Quad-Core 4GB RAM 32GB Storage</em></h2>
    <p>Price: <em>$439.12</em></p>
    <div class="qty-block">
      <div class="qty">
        <input type="text" name="qty" maxlength="12" value="1" title="" class="input-text" />
        <div class="qty_inc_dec">
          <i class="increment" onclick="incrementQty()">+</i>
          <i class="decrement" onclick="decrementQty()">-</i>
        </div>
      </div>
      <button type="button" title="Add to Cart" class="btn-cart">Add to Cart</button>
    </div>
  </div>
</div>

<div class="container">
  <h1>Holiday <strong>Deals</strong></h1>
  <div class="cart-button">
    <img src="http://www.milanmilosev.com/external/codepen/img/cart.png" width="30" height="30">
    <span class="cart-qty">1</span> </div>
  <div class="item">
    <img src="http://www.milanmilosev.com/external/codepen/img/asus.png" alt="">
    <h2>ASUS E200HA-UB02-GD<em>Intel Quad-Core 4GB RAM 32GB Storage</em></h2>
    <p>Price: <em>$439.12</em></p>
    <div class="qty-block">
      <div class="qty">
        <input type="text" name="qty" maxlength="12" value="1" title="" class="input-text" />
        <div class="qty_inc_dec">
          <i class="increment" onclick="incrementQty()">+</i>
          <i class="decrement" onclick="decrementQty()">-</i>
        </div>
      </div>
      <button type="button" title="Add to Cart" class="btn-cart">Add to Cart</button>
    </div>
  </div>
</div>

<div class="container">
  <h1>Holiday <strong>Deals</strong></h1>
  <div class="cart-button">
    <img src="http://www.milanmilosev.com/external/codepen/img/cart.png" width="30" height="30">
    <span class="cart-qty">1</span> </div>
  <div class="item">
    <img src="http://www.milanmilosev.com/external/codepen/img/asus.png" alt="">
    <h2>ASUS E200HA-UB02-GD<em>Intel Quad-Core 4GB RAM 32GB Storage</em></h2>
    <p>Price: <em>$439.12</em></p>
    <div class="qty-block">
      <div class="qty">
        <input type="text" name="qty" maxlength="12" value="1" title="" class="input-text" />
        <div class="qty_inc_dec">
          <i class="increment" onclick="incrementQty()">+</i>
          <i class="decrement" onclick="decrementQty()">-</i>
        </div>
      </div>
      <button type="button" title="Add to Cart" class="btn-cart">Add to Cart</button>
    </div>
  </div>
</div>

Answer 1

简短的回答是否定的。您无法使用当前设置进行操作。为什么？每个物品都应该有一个唯一的标识符。只需说我们将在您的容器div中附加唯一标识符（因为这似乎是每个项目的父对象）。

当然，我会做不同的操作并添加一个id，但是仅出于演示目的，我将html结构制作为与您的结构最接近。

1. 为您的容器class =“ container-1”添加一个数字/ id作为类。创建dom时自动增加数字

2. 在增量/减量函数中传递数字/ id。这将有助于确定您要使用的控件。

3. 更改查询选择器以在查询选择器子句中获取容器父级 例如var cardQty = document.querySelector（'。container-'+ num +'.cart-qty'）;

然后您就去了。现在正在工作。

function incrementQty(num) {
  var targetQtyTextbox= '.container-'+num+' input[name="qty"]';
  var value = document.querySelector(targetQtyTextbox).value;
  var cardQty = document.querySelector('.container-'+num+' .cart-qty');
  value = isNaN(value) ? 1 : value;
  value++;
  document.querySelector(targetQtyTextbox).value = value;
  cardQty.innerHTML = value;
  cardQty.classList.add("rotate-x");
}

function decrementQty(num) {
  var targetQtyTextbox= '.container-'+num+' input[name="qty"]';
  var value = document.querySelector(targetQtyTextbox).value;
  var cardQty = document.querySelector('.container-'+num+' .cart-qty');
  value = isNaN(value) ? 1 : value;
  value > 1 ? value-- : value;
  document.querySelector(targetQtyTextbox).value = value;
  cardQty.innerHTML = value;
  cardQty.classList.add("rotate-x");
}

function removeAnimation(e) {
  e.target.classList.remove("rotate-x");
}

const counter = document.querySelector(".cart-qty");
counter.addEventListener("animationend", removeAnimation);

$text-color: #2a2a2a;
$bg-color: #f2eee9;
*,
*:before,
*:after {
  box-sizing: border-box;
}

@mixin clearfix {
  content: '';
  display: table;
  clear: both;
}

body {
  font-family: 'Open Sans', sans-serif;
  color: $text-color;
  display: flex;
  height: 100vh;
  align-items: center;
  font-size: 14px;
  background: $bg-color;
  background-size: cover;
}

.container {
  position: relative;
  width: 100%;
  max-width: 280px;
  margin: 0 auto;
  &:after {
    @include clearfix;
  }
}

h1 {
  display: inline-block;
  background-color: $text-color;
  color: #fff;
  font-size: 20px;
  font-weight: normal;
  text-transform: uppercase;
  padding: 4px 20px;
  float: left;
}

.item {
  background-color: #fff;
  padding: 10px;
  box-shadow: 0 1.5px 4px rgba(0, 0, 0, 0.24), 0 1.5px 6px rgba(0, 0, 0, 0.12);
  border: 1px solid #FFFEFD;
  img {
    display: block;
    margin: auto;
    padding: 20px;
    width: 180px;
  }
  h2 {
    font-size: 1.1em;
    font-weight: normal;
    display: block;
    border-bottom: 1px solid #ccc;
    margin: 10px 0 10px 0;
    padding: 0 0 5px 0;
    em {
      display: block;
      line-height: 1.6;
      font-size: .8em;
    }
  }
}

.cart-button {
  float: right;
  margin: 12px 15px 0 0;
  img {
    width: 30px;
    height: 30px;
    margin: 0 auto;
    display: block;
    color: #888;
  }
  .cart-qty {
    background: #ff5252;
    border-radius: 50%;
    color: #fff;
    display: block;
    font-size: .8em;
    line-height: 17px;
    position: absolute;
    text-align: center;
    top: 11px;
    right: 10px;
    height: 17px;
    width: 17px;
  }
}

.qty-block {
  margin-top: 20px;
}

.qty {
  float: left;
  width: 80px;
  margin-right: 10px;
  user-select: none;
}

.increment,
.decrement {
  .qty_inc_dec & {
    float: left;
    text-align: center;
    width: 30px;
    cursor: pointer;
    font-size: 1.2em;
    line-height: 20px;
    height: 25px;
    vertical-align: middle;
    background-color: #fff;
    border: 1px solid #ccc;
  }
}

.increment {
  .qty_inc_dec & {
    border-bottom: 0;
    line-height: 25px;
  }
}

.qty_inc_dec {
  float: left;
  width: 10px;
  height: 50px;
  display: inline-block;
}

input[type="text"] {
  .qty & {
    float: left;
    font-family: "Open Sans", sans-serif;
    outline: 0;
    font-size: 1.2em;
    text-align: center;
    width: 50px;
    height: 50px;
    color: $text-color;
    line-height: 40px;
    border: 1px solid #ccc;
    border-right: 0;
  }
}

button[type="button"] {
  cursor: pointer;
  width: 168px;
  border: none;
  color: $text-color;
  background: #fff;
  height: 50px;
  font-size: 1.2em;
  font-family: 'Open Sans', sans-serif;
  transition: all .2s;
  border: 1px solid #ccc;
  box-shadow: 0 1px 2px #fff;
  &:hover {
    box-shadow: 0 1px 2px #cbc3ba;
  }
  &:active,
  &:focus {
    outline: none;
  }
}

.rotate-x {
  animation-duration: .6s;
  animation-name: rotate-x;
}

@keyframes rotate-x {
  from {
    transform: rotateY(0deg);
  }
  to {
    transform: rotateY(360deg);
  }
}

<div class="container-1">
  <h1>Holiday <strong>Deals</strong></h1>
  <div class="cart-button">
    <img src="http://www.milanmilosev.com/external/codepen/img/cart.png" width="30" height="30">
    <span class="cart-qty">1</span> </div>
  <div class="item">
    <img src="http://www.milanmilosev.com/external/codepen/img/asus.png" alt="">
    <h2>ASUS E200HA-UB02-GD<em>Intel Quad-Core 4GB RAM 32GB Storage</em></h2>
    <p>Price: <em>$439.12</em></p>
    <div class="qty-block">
      <div class="qty">
        <input type="text" name="qty" maxlength="12" value="1" title="" class="input-text" />
        <div class="qty_inc_dec">
          <i class="increment" onclick="incrementQty(1)">+</i>
          <i class="decrement" onclick="decrementQty(1)">-</i>
        </div>
      </div>
      <button type="button" title="Add to Cart" class="btn-cart">Add to Cart</button>
    </div>
  </div>
</div>

<div class="container-2">
  <h1>Holiday <strong>Deals</strong></h1>
  <div class="cart-button">
    <img src="http://www.milanmilosev.com/external/codepen/img/cart.png" width="30" height="30">
    <span class="cart-qty">1</span> </div>
  <div class="item">
    <img src="http://www.milanmilosev.com/external/codepen/img/asus.png" alt="">
    <h2>ASUS E200HA-UB02-GD<em>Intel Quad-Core 4GB RAM 32GB Storage</em></h2>
    <p>Price: <em>$439.12</em></p>
    <div class="qty-block">
      <div class="qty">
        <input type="text" name="qty" maxlength="12" value="1" title="" class="input-text" />
        <div class="qty_inc_dec">
          <i class="increment" onclick="incrementQty(2)">+</i>
          <i class="decrement" onclick="decrementQty(2)">-</i>
        </div>
      </div>
      <button type="button" title="Add to Cart" class="btn-cart">Add to Cart</button>
    </div>
  </div>
</div>

<div class="container-3">
  <h1>Holiday <strong>Deals</strong></h1>
  <div class="cart-button">
    <img src="http://www.milanmilosev.com/external/codepen/img/cart.png" width="30" height="30">
    <span class="cart-qty">1</span> </div>
  <div class="item">
    <img src="http://www.milanmilosev.com/external/codepen/img/asus.png" alt="">
    <h2>ASUS E200HA-UB02-GD<em>Intel Quad-Core 4GB RAM 32GB Storage</em></h2>
    <p>Price: <em>$439.12</em></p>
    <div class="qty-block">
      <div class="qty">
        <input type="text" name="qty" maxlength="12" value="1" title="" class="input-text" />
        <div class="qty_inc_dec">
          <i class="increment" onclick="incrementQty(3)">+</i>
          <i class="decrement" onclick="decrementQty(3)">-</i>
        </div>
      </div>
      <button type="button" title="Add to Cart" class="btn-cart">Add to Cart</button>
    </div>
  </div>
</div>

Answer 2

document.querySelector仅选择第一个匹配的CSS选择器。

因此，您将要使用document.querySelectorAll，并将增量/减量处理程序附加到每个数组元素。

Answer 3

function incrementQty(_this) {
  // get All increment button
  var increment = document.querySelectorAll(".increment"); 
  // get index click button      
  var index = [].indexOf.call(increment, _this)
  // get qty to index
  var value = document.querySelectorAll('input[name="qty"]')[index].value;
  // get cart-qty to index
  var cardQty = document.querySelectorAll(".cart-qty")[index];
  value = isNaN(value) ? 1 : value;
  value++;
  document.querySelectorAll('input[name="qty"]')[index].value = value;
  cardQty.innerHTML = value;
  cardQty.classList.add("rotate-x");
}

function decrementQty(_this) {
  var decrement = document.querySelectorAll(".decrement");
  var index = [].indexOf.call(decrement, _this)
  var value = document.querySelectorAll('input[name="qty"]')[index].value;
  var cardQty = document.querySelectorAll(".cart-qty")[index];
  value = isNaN(value) ? 1 : value;
  value > 1 ? value-- : value;
  document.querySelectorAll('input[name="qty"]')[index].value = value;
  cardQty.innerHTML = value;
  cardQty.classList.add("rotate-x");
}

function removeAnimation(e) {
  e.target.classList.remove("rotate-x");
}

const counter = document.querySelector(".cart-qty");
counter.addEventListener("animationend", removeAnimation);

$text-color: #2a2a2a;
$bg-color: #f2eee9;
*,
*:before,
*:after {
  box-sizing: border-box;
}

@mixin clearfix {
  content: '';
  display: table;
  clear: both;
}

body {
  font-family: 'Open Sans', sans-serif;
  color: $text-color;
  display: flex;
  height: 100vh;
  align-items: center;
  font-size: 14px;
  background: $bg-color;
  background-size: cover;
}

.container {
  position: relative;
  width: 100%;
  max-width: 280px;
  margin: 0 auto;
  &:after {
    @include clearfix;
  }
}

h1 {
  display: inline-block;
  background-color: $text-color;
  color: #fff;
  font-size: 20px;
  font-weight: normal;
  text-transform: uppercase;
  padding: 4px 20px;
  float: left;
}

.item {
  background-color: #fff;
  padding: 10px;
  box-shadow: 0 1.5px 4px rgba(0, 0, 0, 0.24), 0 1.5px 6px rgba(0, 0, 0, 0.12);
  border: 1px solid #FFFEFD;
  img {
    display: block;
    margin: auto;
    padding: 20px;
    width: 180px;
  }
  h2 {
    font-size: 1.1em;
    font-weight: normal;
    display: block;
    border-bottom: 1px solid #ccc;
    margin: 10px 0 10px 0;
    padding: 0 0 5px 0;
    em {
      display: block;
      line-height: 1.6;
      font-size: .8em;
    }
  }
}

.cart-button {
  float: right;
  margin: 12px 15px 0 0;
  img {
    width: 30px;
    height: 30px;
    margin: 0 auto;
    display: block;
    color: #888;
  }
  .cart-qty {
    background: #ff5252;
    border-radius: 50%;
    color: #fff;
    display: block;
    font-size: .8em;
    line-height: 17px;
    position: absolute;
    text-align: center;
    top: 11px;
    right: 10px;
    height: 17px;
    width: 17px;
  }
}

.qty-block {
  margin-top: 20px;
}

.qty {
  float: left;
  width: 80px;
  margin-right: 10px;
  user-select: none;
}

.increment,
.decrement {
  .qty_inc_dec & {
    float: left;
    text-align: center;
    width: 30px;
    cursor: pointer;
    font-size: 1.2em;
    line-height: 20px;
    height: 25px;
    vertical-align: middle;
    background-color: #fff;
    border: 1px solid #ccc;
  }
}

.increment {
  .qty_inc_dec & {
    border-bottom: 0;
    line-height: 25px;
  }
}

.qty_inc_dec {
  float: left;
  width: 10px;
  height: 50px;
  display: inline-block;
}

input[type="text"] {
  .qty & {
    float: left;
    font-family: "Open Sans", sans-serif;
    outline: 0;
    font-size: 1.2em;
    text-align: center;
    width: 50px;
    height: 50px;
    color: $text-color;
    line-height: 40px;
    border: 1px solid #ccc;
    border-right: 0;
  }
}

button[type="button"] {
  cursor: pointer;
  width: 168px;
  border: none;
  color: $text-color;
  background: #fff;
  height: 50px;
  font-size: 1.2em;
  font-family: 'Open Sans', sans-serif;
  transition: all .2s;
  border: 1px solid #ccc;
  box-shadow: 0 1px 2px #fff;
  &:hover {
    box-shadow: 0 1px 2px #cbc3ba;
  }
  &:active,
  &:focus {
    outline: none;
  }
}

.rotate-x {
  animation-duration: .6s;
  animation-name: rotate-x;
}

@keyframes rotate-x {
  from {
    transform: rotateY(0deg);
  }
  to {
    transform: rotateY(360deg);
  }
}

<div class="container">
  <h1>Holiday <strong>Deals</strong></h1>
  <div class="cart-button">
    <img src="http://www.milanmilosev.com/external/codepen/img/cart.png" width="30" height="30">
    <span class="cart-qty">1</span> </div>
  <div class="item">
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