动态计算字段中的字符数 [英] Count characters in field dynamically

问题描述

我想动态计算textarea字段中的字符，我知道有一个类似的问题，但我想知道它是否可以从某个数字向0计数，例如在Twitter上写一条推文。 / p>

这段代码可能是javascript，PHP，对我来说并不重要。

解决方案

这应该可以帮到你。以下是关于使用情况的教程 - 演示如下：

用法：

 < input name = textonKeyDown =CountLeft（this.form.text，this.form.left，50）; 
 onKeyUp =CountLeft（this.form.text，this.form.left，50）;> 
  

Javascript：

 < SCRIPT LANGUAGE =JavaScript> 
 
函数CountLeft（field，count，max）
 {
 if（field.value.length> max）
 field.value = field.value.substring （0，max）; 
 else 
 count.value = max  -  field.value.length; 
} 
 
< / SCRIPT> 
  

演示 - 信用www.reconn.us

希望这有帮助。

I would like to count characters in a form textarea field dynamically, I know there is a similar question about this but I am wondering if it can count from a certain number towards 0, as example while writing a tweet on Twitter.

This code could be in javascript, PHP, it doesn't really matter to me.

解决方案

This should help you out. Here is a tutorial regarding usage - a demo is found below:

Usage:

<input name="text" onKeyDown="CountLeft(this.form.text, this.form.left,50);"
                   onKeyUp="CountLeft(this.form.text,this.form.left,50);">

Javascript:

<SCRIPT LANGUAGE="JavaScript">

 function CountLeft(field, count, max) 
 {
     if (field.value.length > max)
         field.value = field.value.substring(0, max);
     else
         count.value = max - field.value.length;
 }

</SCRIPT>

Demo - Credit to www.reconn.us

Hope this helps.

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