仅允许数字和一位小数 [英] Allowing only numbers and one decimal

问题描述

伙计和女孩我有这段JavaScript代码，只允许数字和一个小数周期。我遇到的问题是，当我切换到我的文本框控件时，它会突出显示该值，但我按了退格键以擦除然后输入一个数字。这是我想要阻止的额外击键。

Guys and gals i have this piece of JavaScript code that only allows for numbers and one decimal period. The problem i'm having is that when i tab over to my textbox controls it highlights the value but i have press backspace to erase then enter a number. That is an extra keystroke that i want to prevent.

找到创建它的人的道具（ http://www.coderanch.com/t/114528/HTML-CSS-JavaScript/decimal-point-restriction ）这是代码。我把它放在keyUp事件上。

Props to the guy who created it found (http://www.coderanch.com/t/114528/HTML-CSS-JavaScript/decimal-point-restriction) and here is the code. I put this on keyUp event.

 <script>
  // Retrieve last key pressed.  Works in IE and Netscape.
  // Returns the numeric key code for the key pressed.
  function getKey(e)
  {
    if (window.event)
       return window.event.keyCode;
    else if (e)
       return e.which;
    else
       return null;
  }
  function restrictChars(e, obj)
  {
    var CHAR_AFTER_DP = 2;  // number of decimal places
    var validList = "0123456789.";  // allowed characters in field
    var key, keyChar;
    key = getKey(e);
    if (key == null) return true;
    // control keys
    // null, backspace, tab, carriage return, escape
    if ( key==0 || key==8 || key==9 || key==13 || key==27 )
       return true;
    // get character
    keyChar = String.fromCharCode(key);
    // check valid characters
    if (validList.indexOf(keyChar) != -1)
    {
      // check for existing decimal point
      var dp = 0;
      if( (dp = obj.value.indexOf( ".")) > -1)
      {
        if( keyChar == ".")
          return false;  // only one allowed
        else
        {
          // room for more after decimal point?
          if( obj.value.length - dp <= CHAR_AFTER_DP)
            return true;
        }
      }
      else return true;
    }
    // not a valid character
    return false;
  }
</script>

推荐答案

如果你不能使用已经稳定的井知道库，你可以尝试这样的事情：

If you can't use an already stable and well-know library, you can try something like this:

document.write('<input id="inputField" onkeyup="run(this)" />');

function run(field) {
    setTimeout(function() {
        var regex = /\d*\.?\d?/g;
        field.value = regex.exec(field.value);
    }, 0);
}

我知道它不会阻止出现错误的字符，但它有效。

I know it doesn't prevent the wrong char to appear, but it works.

PS：那个 setTimeout（...，0）是一个在值之后执行函数的技巧该字段已被修改。

PS: that setTimeout(..., 0) is a trick to execute the function after the value of the field has already been modified.

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