禁用按钮，每当文本字段为空动态 [英] Disable button whenever a text field is empty dynamically

问题描述

下面是我的code：

<input type="text" onkeyup="if(this.value.length > 0) document.getElementById('start_button').disabled = false; else document.getElementById('start_button').disabled = true;"/>
<input type="button" value="Click to begin!" id="start_button" disabled/>

这工作，但仍不能有效，因为用户可以删除文本框中的文本，点击按钮同时他持有DELETE键。有没有更有效的方式来实现这一目标使用JavaScript？

This works but still not efficient since the user can delete the text inside the text box and click the button while he's holding on DELETE key. Is there a more efficient way to achieve this using javascript?

推荐答案

添加一个检查单击按钮时，看看是否有任何文字。如果没有，弹出一个警告框（或反馈一些其他形式）来告诉用户输入的数据，不做按钮的功能。

Add a check when the button is clicked to see if there is any text. If there isn't, pop up an alert box (or some other form of feedback) to tell the user to enter data, and don't do the button functionality.

例如：

<input id="myText" type="text" onkeyup="stoppedTyping()">
<input type="button" value="Click to begin!" id="start_button" onclick="verify()" disabled/> 

<script type="text/javascript">
    function stoppedTyping(){
        if(this.value.length > 0) { 
            document.getElementById('start_button').disabled = false; 
        } else { 
            document.getElementById('start_button').disabled = true;
        }
    }
    function verify(){
        if myText is empty{
            alert "Put some text in there!"
            return
        }
        else{
            do button functionality
        }
    }
</script>

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