如何强制输入只允许字母? [英] How to force input to only allow Alpha Letters?

问题描述

此处使用 jQuery，但无法阻止将数字输入到输入字段中

using jQuery here, however unable to prevent numbers from being typed into the input field

http://codepen.io/leongaban/pen/owbjg

输入

<input type="text" name="field" maxlength="8"
    title="Only Letters"
    value="Type Letters Only"
    onkeydown="return alphaOnly(event);"
    onblur="if (this.value == '') {this.value = 'Type Letters Only';}"
    onfocus="if (this.value == 'Type Letters Only') {this.value = '';}"/>

jQuery

function alphaOnly(event) {

  alert(event);

  var key;

  if (window.event) {
    key = window.event.key;
  } else if (e) {
    key = e.which;
  }
  //var key = window.event.key || event.key;
  alert(key.value);
  return ((key >= 65 && key <= 90) || (key >= 95 && key <= 122));

}

我在这里看到了很多关于如何限制为仅数字的示例，并且我使用了正确的 a-z 和 A-Z 键码.你看到我做错了什么吗?

I've seen plenty of examples here on how to restrict to only Numbers, and I'm using the correct key codes for a-z and A-Z. Do you see what I'm doing wrong?

推荐答案

event.key 属性给了我一个未定义的值.相反，我使用了 event.keyCode:

The property event.key gave me an undefined value. Instead, I used event.keyCode:

function alphaOnly(event) {
  var key = event.keyCode;
  return ((key >= 65 && key <= 90) || key == 8);
};

请注意，8 的值用于退格键.

Note that the value of 8 is for the backspace key.

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