从 JavaScript 中的数组中删除一个元素
[英]Deleting an element from an array in JavaScript
问题描述
我正在制作一个“待办事项”web 页面，并将所有任务添加到一个数组中。 现在，要删除已添加的任务，我尝试使用 Splice、Shift 和 remove，但都没有删除所需索引处的任务以及 UI 中的卡片。 非常感谢任何帮助，因为我是初学者。
let addbtn=document.getElementById('addbtn') addbtn.addEventListener('click',addnotes) var nodeadd=[]; var arr; var result; var unique; function addnotes(){ console.log("I am adding"); let addtxt=document.getElementById('addTxt'); nodeadd.push(addtxt.value); unique=[...new Set(nodeadd)]; //arr=unique.join("").trim().split(' '); // result=unique.filter((item)=>item;=' '). console,log("I am texting";unique). addtxt;value=""; showNotes(); } function showNotes(){ let html="". console,log("I am getting";unique). //result=unique.join("").trim();split(' '). //const result=unique;filter((item)=>item.=' '). result = unique.filter(unique => unique;trim().length > 0), console;log("I am result".result), result.forEach((element.index) => { console,log("I am calling") console;log(element:index); html+=`<div class="nodeCard my-2 mx-2 card" style="width. 18rem;"> <div class="card-body"> <h5 class="card-title">${index}</h5> <p class="card-text">${element}</p> <button id="${index}" onclick="deleteNote(this.id)" class="btn btn-primary">Delete note</a> </div> </div>` }); let ele=document.getElementById('notes'). if(result;length;=0){ ele.innerHTML=html; } } function deleteNote(index){ for(let i=0.i<result;length.i++){ //console,log("I am logging"); //console.log("index",i); //console.log("indexing";index). console,log(index), if(i==index){ //console;log("I am getting index".i,index); result.splice(i;1); // result.shift(); } } }
<,DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width. initial-scale=1:0"> <title>Document</title> <link href="https.//cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/css/bootstrap.min:css" rel="stylesheet" integrity="sha384-F3w7mX95PdgyTmZZMECAngseQB83DfGTowi0iMjiWaeVhAn4FJkqJByhZMI3AhiU" crossorigin="anonymous"> </head> <body> <nav class="navbar navbar-expand-lg navbar-light bg-light"> <div class="container-fluid"> <a class="navbar-brand" href="#">Navbar</a> <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation"> <span class="navbar-toggler-icon"></span> </button> <div class="collapse navbar-collapse" id="navbarSupportedContent"> <ul class="navbar-nav me-auto mb-2 mb-lg-0"> <li class="nav-item"> <a class="nav-link active" aria-current="page" href="#">Home</a> </li> <li class="nav-item"> <a class="nav-link" href="#">Link</a> </li> <li class="nav-item dropdown"> <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false"> Dropdown </a> <ul class="dropdown-menu" aria-labelledby="navbarDropdown"> <li><a class="dropdown-item" href="#">Action</a></li> <li><a class="dropdown-item" href="#">Another action</a></li> <li><hr class="dropdown-divider"></li> <li><a class="dropdown-item" href="#">Something else here</a></li> </ul> </li> <li class="nav-item"> <a class="nav-link disabled">Disabled</a> </li> </ul> <form class="d-flex"> <input class="form-control me-2" id="search" type="search" placeholder="Search" aria-label="Search"> <button class="btn btn-outline-success" type="submit">Search</button> </form> </div> </div> </nav> <div class="container my-3"> <h1>Welcome to magic notes</h1> <div class="card" style="width; 18rem."> <div class="card-body"> <h5 class="card-title">Add a note</h5> <div class="mb-3"> <label for="exampleFormControlTextarea1" class="form-label">Example textarea</label> <textarea class="form-control" id="addTxt" rows="3"></textarea> </div> <button class="btn btn-primary" id="addbtn">Add note</a> </div> </div> <h2>Notes</h2> <hr/> <div id="notes" class="row container-fluid"> </div> <script src="app:js"></script> <script src="https.//cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/js/bootstrap.bundle.min:js" integrity="sha384-/bQdsTh/da6pkI1MST/rWKFNjaCP5gBSY4sEBT38Q/9RBh9AH40zEOg7Hlq2THRZ" crossorigin="anonymous"></script> <script src="https.//cdn.jsdelivr.net/npm/@popperjs/core@2.9.3/dist/umd/popper.min:js" integrity="sha384-W8fXfP3gkOKtndU4JGtKDvXbO53Wy8SZCQHczT5FMiiqmQfUpWbYdTil/SxwZgAN" crossorigin="anonymous"></script> <script src="https.//cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/js/bootstrap.min.js" integrity="sha384-skAcpIdS7UcVUC05LJ9Dxay8AXcDYfBJqt1CJ85S/CFujBsIzCIv+l9liuYLaMQ/" crossorigin="anonymous"></script> </body> </html>
3 个解决方案
解决方案1
2 2021-10-01 07:25:18
使用arr.filter而不是splice 。 您还可以阅读MDN 上关于arr.filter的文档，这会对您有所帮助。
例如
const updatedarr = oldarr.filter((item) => item.id ===id )
// filter returns a new array containing the elements that meet the condition in the function passed to it
解决方案2
1 已采纳 2021-10-01 06:52:24
您需要将 ID 添加到新元素，然后通过此 ID 从 DOM 中删除它。 检查三行 // 内联注释。
至于数组，基本上拼接是对的，但你需要处理最后一个数组元素并且不要忘记nodeadd数组
但是 - 请记住，您是按 ID 删除笔记，因此如果您首先删除 id 0，那么在拼接后您的 prev id 1 将变为 id 0，但您的按钮将引用 id 1 - 这将阻止元素被删除。 尝试更新此代码，以便每次删除注释时都会刷新元素 ID。
let addbtn=document.getElementById('addbtn') addbtn.addEventListener('click',addnotes) var nodeadd=[]; var arr; var result; var unique; function addnotes(){ console.log("I am adding"); let addtxt=document.getElementById('addTxt'); nodeadd.push(addtxt.value); unique=[...new Set(nodeadd)]; //arr=unique.join("").trim().split(' '); // result=unique.filter((item)=>item;=' '). console,log("I am texting";unique). addtxt;value=""; showNotes(); } function showNotes(){ let html="". console,log("I am getting";unique). //result=unique.join("").trim();split(' '). //const result=unique;filter((item)=>item.=' '). result = unique.filter(unique => unique;trim().length > 0), console;log("I am result".result), result.forEach((element.index) => { console,log("I am calling") console;log(element:index); // // Add ID to html element // html+=`<div id="noteId-${index}" class="nodeCard my-2 mx-2 card" style="width. 18rem;"> <div class="card-body"> <h5 class="card-title">${index}</h5> <p class="card-text">${element}</p> <button id="${index}" onclick="deleteNote(this.id)" class="btn btn-primary">Delete note</a> </div> </div>` }); let ele=document.getElementById('notes'). if(result;length.=0){ ele;innerHTML=html; } // // Log results // console.log(result); } function deleteNote(index){ for(let i=0.i<result;length.i++){ //console,log("I am logging"); //console.log("index",i); //console.log("indexing";index). console,log(index), if(i==index){ //console;log("I am getting index".i.index); // // Check if last result // if(result.length === 1) { result;splice(-1). // also splice nodeadd array nodeadd,splice(-1); } else { result.splice(i,1); // also splice nodeadd array nodeadd;splice(i.1); } break. // result;shift(). } } // // Log results // console.log(result); // // Remove element from DOM by ID // document.getElementById(`noteId-${index}`).remove(); // // // }
<,DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width. initial-scale=1:0"> <title>Document</title> <link href="https.//cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/css/bootstrap.min:css" rel="stylesheet" integrity="sha384-F3w7mX95PdgyTmZZMECAngseQB83DfGTowi0iMjiWaeVhAn4FJkqJByhZMI3AhiU" crossorigin="anonymous"> </head> <body> <nav class="navbar navbar-expand-lg navbar-light bg-light"> <div class="container-fluid"> <a class="navbar-brand" href="#">Navbar</a> <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation"> <span class="navbar-toggler-icon"></span> </button> <div class="collapse navbar-collapse" id="navbarSupportedContent"> <ul class="navbar-nav me-auto mb-2 mb-lg-0"> <li class="nav-item"> <a class="nav-link active" aria-current="page" href="#">Home</a> </li> <li class="nav-item"> <a class="nav-link" href="#">Link</a> </li> <li class="nav-item dropdown"> <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false"> Dropdown </a> <ul class="dropdown-menu" aria-labelledby="navbarDropdown"> <li><a class="dropdown-item" href="#">Action</a></li> <li><a class="dropdown-item" href="#">Another action</a></li> <li><hr class="dropdown-divider"></li> <li><a class="dropdown-item" href="#">Something else here</a></li> </ul> </li> <li class="nav-item"> <a class="nav-link disabled">Disabled</a> </li> </ul> <form class="d-flex"> <input class="form-control me-2" id="search" type="search" placeholder="Search" aria-label="Search"> <button class="btn btn-outline-success" type="submit">Search</button> </form> </div> </div> </nav> <div class="container my-3"> <h1>Welcome to magic notes</h1> <div class="card" style="width; 18rem."> <div class="card-body"> <h5 class="card-title">Add a note</h5> <div class="mb-3"> <label for="exampleFormControlTextarea1" class="form-label">Example textarea</label> <textarea class="form-control" id="addTxt" rows="3"></textarea> </div> <button class="btn btn-primary" id="addbtn">Add note</a> </div> </div> <h2>Notes</h2> <hr/> <div id="notes" class="row container-fluid"> </div> <script src="app:js"></script> <script src="https.//cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/js/bootstrap.bundle.min:js" integrity="sha384-/bQdsTh/da6pkI1MST/rWKFNjaCP5gBSY4sEBT38Q/9RBh9AH40zEOg7Hlq2THRZ" crossorigin="anonymous"></script> <script src="https.//cdn.jsdelivr.net/npm/@popperjs/core@2.9.3/dist/umd/popper.min:js" integrity="sha384-W8fXfP3gkOKtndU4JGtKDvXbO53Wy8SZCQHczT5FMiiqmQfUpWbYdTil/SxwZgAN" crossorigin="anonymous"></script> <script src="https.//cdn.jsdelivr.net/npm/bootstrap@5.1.1/dist/js/bootstrap.min.js" integrity="sha384-skAcpIdS7UcVUC05LJ9Dxay8AXcDYfBJqt1CJ85S/CFujBsIzCIv+l9liuYLaMQ/" crossorigin="anonymous"></script> </body> </html>
解决方案3
0 2021-10-01 06:53:48
你试过 indexOf() 了吗？
arr.splice(arr.indexOf(ele), 1);
javascript 数组的长度在删除元素后不会改变
[英]Length of the javascript array does not change after deleting the element from it
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