e.target.tagName和e.target.dataset的作用是什么

博客介绍了在JavaScript中获取事件源(DOM对象),以及通过DOM对象属性获取标签名,可获取大写标签名,若要小写可用nodeName或转换后比较,还提到用e.target.dataset获取元素的值。

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e.target 取得的是事件发生的对象,即事件源,它是 DOM 对象。

tagName 是 DOM 对象的属性,用于获取 DOM 对象的标签名,取出来是大写的,你要取小写的用 nodeName。或者用toLowerCase()tagName转换成小写之后再进行比较。

e.target.dataset获取元素的值

 <div class="filter">
    <a data-index="1" href="javascript:;">0-100元</a>
    <a data-index="2" href="javascript:;">100-300元</a>
    <a data-index="3" href="javascript:;">300元以上</a>
    <a href="javascript:;">全部区间</a>
  </div>
document.querySelector('.filter').addEventListener('click', e => {
  const{tagName,dataset}=e.target
  if (tagName==='A'){
    let arr=goodsList
    if(dataset.index==='1'){
   arr= goodsList.filter(item =>item.price>0&&item.price<=100)
     } else if(dataset.index==='2'){
   arr= goodsList.filter(item =>item.price>=100&&item.price<=300)
      } else if(dataset.index==='3'){
   arr= goodsList.filter(item =>item.price>=300)
      }
     
    
    render(arr)
  }
})
</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> <script src="../js/goods.js"></script> <style> .goods-list { width: 100%; height: 300px; border: 1px solid #000; overflow: auto; } .clear::after { content: ""; display: block; clear: both; visibility: hidden; height: 0; } .goods { width: 150px; height: 200px; float: left; overflow: hidden; margin: 10px; } .goods>img { width: 100%; } .goods * { pointer-events: none; } table { width: 100%; border-collapse: collapse; } th, td { /* border: 1px solid #000; */ text-align: center; } .step-num>button { width: 30px; height: 30px; font-size: 25px; line-height: 25px; border-radius: 1; } .step-num>input { width: 50px; height: 25px; font-size: 20px; position: relative; top: -2px; border: 1px solid #000; border-left: none; border-right: none; outline: none; text-align: center; } </style> </head> <body> <div class="goods-list clear"></div> <table> <thead> <tr> <th style="width: 60px"><input type="checkbox" id="all" />全选</th> <th style="width: 80px">商品图</th> <th style="width: 300px">商品信息</th> <th>类型</th> <th>单价</th> <th style="width: 120px">数量</th> <th>合计</th> <th>操作 <button class="alldelete">删除</button></th> </tr> </thead> <tbody></tbody> </table> <img class="view-img" style=" display: none; position: fixed; left: 0; top: 0; bottom: 0; right: 0; margin: auto; " /> <script> var goodsList, tbody, id, all, viewImg, alldelete; var shoppingList = []; init(); function init() { goodsList = document.querySelector('.goods-list'); viewImg = document.querySelector('.view-img'); tbody = document.querySelector('tbody'); all = document.querySelector('#all'); alldelete = document.querySelector('.alldelete'); goodsList.innerHTML = list.map((item) => createGoods(item)).join(""); goodsList.addEventListener('click', addGoodsHandler); tbody.addEventListener('input', inputHandler); tbody.addEventListener('click', tbodyClickHandler); all.addEventListener('change', allChangeHandler); viewImg.addEventListener('click', (e) => (viewImg.style.display = 'none')); alldelete.addEventListener('click', allDeleteHandler); } function allDeleteHandler(e) { shoppingList = shoppingList.filter((item) => !item.checked); render(); } function allChangeHandler(e) { shoppingList.forEach((item) => { item.checked = e.target.checked; }); render(); } function createGoods(item) { return ` <div class='goods' id=${item.proid}> <img src=${item.img1}> <div> <span>${item.proname}</span> </div> </div> `; } function addGoodsHandler(e) { if (e.target.className !== 'goods') return; const id = e.target.id; const shopItem = shoppingList.find((item) => item.id === id); if (!shopItem) { const item = list.find((item) => item.proid == id); const data = { id: item.proid, checked: false, img: item.img1, indo: item.desc, type: item.category, pruce: item.originprice, num: 1, total: item.originprice, }; shoppingList.push(data); } else { shopItem.num++; shopItem.total = shopItem.price * shopItem.num; } render(); } function render() { all.checked = shoppingList.every((item) => item.checked); tbody.innerHTML = shoppingList.map((item) => { return `<tr data=${item.id} > <td><input type="checkbox" class='select' ${item.checked ? "checked" : "" }/></td> <td><img src='${item.img}' width='80'/></td> <td><div style='height:70px;overflow:hidden'>${item.info }</div></td> <td>${item.type}</td> <td>¥${item.price.toFixed(2)}</td> <td class='step-num'><button class='subtraction' ${item.num === 1 ? "disabled" : "" }>-</button><input class='step' type='text' value='${item.num }'/><button class='add'>+</button></td> <td>¥${item.total.toFixed(2)}</td> <td><button class='view'>查看</button><button class='delete'>删除</button></td> </tr>` }).join(''); } function tbodyClickHandler(e) { if (!['BUTTON', 'INPUT'].includes(e.target.nodeName)) return; const id = e.target.parentElement.parentElement.getAttribute('data'); const item = shoppingList.find((item) => item.id == id); switch (e.target.className) { case 'subtraction': if (item.num === 1) return; item.num--; item.total = item.price * item.num; break; case 'add': item.num++; item.total = item.price * item.num; break; case 'select': item.checked = e.target.checked; break; case 'view': viewImg.src = item.img; viewImg.style.display = 'block'; return; case 'delete': shoppingList = shoppingList.filter((item) => item.id != id); break; default: return; } render(); } function inputHandler(e) { if (e.target.className !== 'step' || id) return; id = setTimeout(() => { e.target.value = parseInt(e.target.value) || '1'; const proid = e.target.parentElement.parentElement.getAttribute('data'); const item = shoppingList.find((item) => item.id == proid); item.num = Number(e.target.value); item.total = item.price * item.num; clearTimeout(id); id = undefined; render(); }, 1000); } </script> </body> </html>
最新发布
07-26
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