Javascript-单击此按钮连接到功能时，没有任何反应
[英]Javascript - Nothing happens when I click this button connected to a function
问题描述
So, I'm trying to validate an input field, where an input field cannot be empty. 
因此，我正在尝试验证输入字段，其中输入字段不能为空。 If someone doesn't enter any text into the input field and click 'start a new game' button it should display an alert message saying you need to enter a name. 如果有人没有在输入字段中输入任何文本，然后单击“开始新游戏”按钮，它将显示一条警告消息，提示您需要输入名称。
However, my code does not display the alert message for some reason. 但是，由于某些原因，我的代码未显示警报消息。
Here's my code. 这是我的代码。
<html> <head> <title>Tic Tac Toe</title> </head> <script> function myFunction() { if (document.getElementById(“playerNameNew").innerHTML == null) { alert("Name must be filled out"); return false; } } </script> <body> <header> <h1>Tic - Tac - Toe</h1> </header> <h3>Start a new Game</h3> <input type="text" id="playerNameNew" placeholder="Enter your name" required> <button onclick="myFunction()" id="new">Start a New Game</button> </body> </html>
2 个解决方案
解决方案1
4 已采纳 2018-03-13 22:31:22
Three issues: 三个问题：
-
getElementByIdis an object, however, what you really want is to call that function as followgetElementById(...).getElementById是一个对象，但是，您真正想要的是按照getElementById(...)调用该函数。 -
.innerHTMLreturns the HTML rather than the entered value..innerHTML返回HTML而不是输入的值。 - You have to compare against an empty value rather than null (Use the function
.trim()).您必须比较一个空值而不是null（使用.trim()函数）。
Recommendation: Use the function .addEventListener() to bind the click event. 建议：使用函数.addEventListener()绑定click事件。
<html> <head> <title>Tic Tac Toe</title> </head> <script> function myFunction() { if (!document.getElementById("playerNameNew").value.trim()) { alert("Name must be filled out"); return false; } } </script> <body> <header> <h1>Tic - Tac - Toe</h1> </header> <h3>Start a new Game</h3> <input type="text" id="playerNameNew" placeholder="Enter your name" required> <button onclick="myFunction()" id="new">Start a New Game</button> </body> </html>
解决方案2
-1 2018-03-13 22:41:45
if (document.getElementById("playerNameNew").value == '') {
alert("Name must be filled out");
return false;
}
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