zoukankan      html  css  js  c++  java
  • KeyboardEvent keyCode Property

    Definition and Usage

    The keyCode property returns the Unicode character code of the key that triggered the onkeypress event, or the Unicode key code of the key that triggered the onkeydown or onkeyup event.

    The difference between the two code types:

    • Character codes - A number which represents an ASCII character
    • Key codes - A number which represents an actual key on the keyboard

    These types do not always mean the same thing; for example, a lower case "w" and an upper case "W" have the same keyboard code, because the key that is pressed on the keyboard is the same (just "W" = the number "87"), but a different character code because the resulting character is different (either "w" or "W", which is "119" or "87") - See "More Examples" below to better understand it.

    Tip: To find out if the user is pressing a printable key (e.g. "a" or "5"), it is recommended to use this property on the onkeypress event. To find out if the user is pressing a function key (e.g. "F1", "CAPS LOCK" or "Home") use the onkeydown or onkeyup event.

    Note: In Firefox, the keyCode property does not work on the onkeypress event (will only return 0). For a cross-browser solution, use the which property together with keyCode, e.g:

    which

    Tip: For a list of all Unicode characters, please study our Complete Unicode Reference.

    Tip: If you want to convert the returned Unicode value into a character, use the fromCharCode() method.

    Note: This property is read-only.

    Note: Both the keyCode and which property is provided for compatibility only. The latest version of the DOM Events Specification recommend using the key property instead (if available).

    Tip: If you want to find out whether the "ALT", "CTRL", "META" or "SHIFT" key was pressed when a key event occured, use the altKeyctrlKeymetaKey or shiftKeyproperty.

    Example

    Using onkeypress and onkeydown to demonstrate the differences between character codes and keyboard codes:

    <input type="text" onkeypress="uniCharCode(event)" onkeydown="uniKeyCode(event)"> 

    function uniCharCode(event) {
        var char = event.which || event.keyCode;
        document.getElementById("demo").innerHTML = "Unicode CHARACTER code: " + char;
    }

    function uniKeyCode(event) {
        var key = event.keyCode;
        document.getElementById("demo2").innerHTML = "Unicode KEY code: " + key;
    }

    When pressing the "a" key on the keyboard (not using caps lock), the result of char and key will be:

    Unicode CHARACTER code: 97
    Unicode KEY code: 65
    https://www.w3schools.com/jsref/event_key_keycode.asp请参考官方网站
  • 相关阅读:
    PHP实现微信小程序人脸识别刷脸登录功能
    thinkphp3.2.3中设置路由,优化url
    ThinkPHP URL 路由简介
    在 Linux 下搭建 Git 服务器
    图解 Android 广播机制 狼人:
    手机系统竞争背后的利益竞逐 狼人:
    你必须知道的Windows Phone 7开发 狼人:
    展望Android之前世今生 狼人:
    在美做开发多年,写给国内iPhone开发新手 狼人:
    NDK入门项目实战 狼人:
  • 原文地址:https://www.cnblogs.com/woodyliang/p/7527929.html
Copyright © 2011-2022 走看看