Javascript提示/文本框只有数字 [英] Javascript prompt/textbox only numbers

问题描述

嘿，我只是学习javascript，我有一些html和css的背景。

我不知道如何只允许数字值输入提示，或检查它的一个数字还是不是重新提示如果没有。

解决方案

您已经有了一个很好的答案。

假设您的号码字段如下所示：

code>< input type =textname =num_fldid =num_fldonchange =return chkNum（）; />

<$ p

$ p> function chkNum（）
{
var rc = false;

if（！isNaN（parseFloat（n））&& isFinite（n））
{
rc = true;
}
else
{
document.getElementById（num_fld）。value = 0;
}
return rc;
}


此函数检查数字是否真的是一个数字，与输入，所以坏的值不停留在原地。 Offhand我不太确定如果返回false阻止数字被输入（类似在验证函数。）我相信从我的测试，返回false确实影响了在字段中，但我不是100％确定。

您也可以在失败时更改输入字段的背景和/或文本颜色（测试的else部分，因此用户注意到错误。 code> alert（）; 适合测试，但会混淆您的网站在生产中的外观。

Hey guys I'm just learning javascript, I have some html and css background though.

I can't figure out how to allow only number values to be entered into a prompt, or check if its a number or not than re prompt if its not. Also the same goes for a textbox.

解决方案

You already have a good answer. This answer is another look at things you can do.

Assuming your number field is like the following

<input type="text" name="num_fld" id="num_fld" onchange="return chkNum();" />

and you've defined a javascript function like so

function chkNum()
{
   var rc = false;

   if(!isNaN(parseFloat(n)) && isFinite(n))
   {
     rc = true;
   }
   else
   {
      document.getElementById("num_fld").value = 0;
   }
   return rc;
}

This function checks to see if the number is really a number, but also monkeys with the input, so the bad value does not stay in place. Offhand I am not quite sure if returning false prevents the number from being entered (kind of like in a validate function.) I believe from my testing that returning false does affect what is in the field, but I am not 100% sure of that.

You could also alter the background and/or text color of the input field upon failure (the else part of the test, so the user notices something is wrong. alert(); is good for testing, but kind of messes up the look of your site in production.

这篇关于Javascript提示/文本框只有数字的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！