javascript addEventlistener";点击";不起作用
我正在制作一个待办事项列表作为Chrome的新标签扩展javascript addEventlistener";点击";不起作用,javascript,html,dom,google-chrome-extension,indexeddb,Javascript,Html,Dom,Google Chrome Extension,Indexeddb,我正在制作一个待办事项列表作为Chrome的新标签扩展 <head> </head> <body> <h2 id="toc-final">To Do List</h2> <ul id="todoItems"></ul> <input type="text" id="todo" name="todo" placeholder="What do you need to do?" sty
<head>
</head>
<body>
<h2 id="toc-final">To Do List</h2>
<ul id="todoItems"></ul>
<input type="text" id="todo" name="todo" placeholder="What do you need to do?" style="width: 200px;">
<button id="newitem" value="Add Todo Item">Add</button>
<script type="text/javascript" src="indexdb.js"></script>
</body>
</html>
我的html文件:
<head>
</head>
<body>
<h2 id="toc-final">To Do List</h2>
<ul id="todoItems"></ul>
<input type="text" id="todo" name="todo" placeholder="What do you need to do?" style="width: 200px;">
<button id="newitem" value="Add Todo Item">Add</button>
<script type="text/javascript" src="indexdb.js"></script>
</body>
</html>
为什么当我单击按钮w/id=“newitem”?时什么都没有发生?附加函数时,您首先执行它,然后将返回值
未定义
附加到事件。删除括号:
<head>
</head>
<body>
<h2 id="toc-final">To Do List</h2>
<ul id="todoItems"></ul>
<input type="text" id="todo" name="todo" placeholder="What do you need to do?" style="width: 200px;">
<button id="newitem" value="Add Todo Item">Add</button>
<script type="text/javascript" src="indexdb.js"></script>
</body>
</html>
.addEventListener("click", addTodo, false);
当您将addTodo()
作为参数时,您并没有传递函数本身。它要做的第一件事是执行函数并使用返回值作为参数
<head>
</head>
<body>
<h2 id="toc-final">To Do List</h2>
<ul id="todoItems"></ul>
<input type="text" id="todo" name="todo" placeholder="What do you need to do?" style="width: 200px;">
<button id="newitem" value="Add Todo Item">Add</button>
<script type="text/javascript" src="indexdb.js"></script>
</body>
</html>
由于没有返回
语句的函数隐式导致未定义
,因此原始代码实际上正在运行函数,然后附加以下内容:
<head>
</head>
<body>
<h2 id="toc-final">To Do List</h2>
<ul id="todoItems"></ul>
<input type="text" id="todo" name="todo" placeholder="What do you need to do?" style="width: 200px;">
<button id="newitem" value="Add Todo Item">Add</button>
<script type="text/javascript" src="indexdb.js"></script>
</body>
</html>
.addEventListener("click", undefined, false);
不要使用两个
DOMContentLoaded
侦听器,而是尝试一个
<head>
</head>
<body>
<h2 id="toc-final">To Do List</h2>
<ul id="todoItems"></ul>
<input type="text" id="todo" name="todo" placeholder="What do you need to do?" style="width: 200px;">
<button id="newitem" value="Add Todo Item">Add</button>
<script type="text/javascript" src="indexdb.js"></script>
</body>
</html>
更改此项:
<head>
</head>
<body>
<h2 id="toc-final">To Do List</h2>
<ul id="todoItems"></ul>
<input type="text" id="todo" name="todo" placeholder="What do you need to do?" style="width: 200px;">
<button id="newitem" value="Add Todo Item">Add</button>
<script type="text/javascript" src="indexdb.js"></script>
</body>
</html>
window.addEventListener("DOMContentLoaded", init, false);
window.addEventListener('DOMContentLoaded', function () {
document.getElementById("newitem").addEventListener("click", addTodo(), false);
});
为此:
<head>
</head>
<body>
<h2 id="toc-final">To Do List</h2>
<ul id="todoItems"></ul>
<input type="text" id="todo" name="todo" placeholder="What do you need to do?" style="width: 200px;">
<button id="newitem" value="Add Todo Item">Add</button>
<script type="text/javascript" src="indexdb.js"></script>
</body>
</html>
window.addEventListener('DOMContentLoaded', function () {
init();
document.getElementById("newitem").addEventListener("click", addTodo, false);
});
如果控制台中出现任何错误,是否可以在
addTodo
顶部记录消息?没有人能用“不工作”来做什么。addEventListener中的addTodo()
将扩展到function(){addTodo();}
@TbWill4321我的道歉。关于数据库,我的类函数中还有更多的问题。我让它工作了。谢谢你的帮助,括号也是个问题。为什么addTodo()
不起作用?如果是一个愚蠢的问题,很抱歉,我是Javascript新手。