在 cookie 中保存下拉菜单选择? [英] Saving dropdown menu selection in a cookie?

问题描述

我已经多次看到这个帖子，但我根本无法让代码运行.我需要帮助让这个下拉菜单将其设置保存到一个 cookie，所以当用户再次访问该站点时，他们之前的选择会被保留.

I've seen this posted a few times, but I wasn't able to get the code working at all. I need help making this drop down menu save its settings to a cookie, so when the user visits the site again, their previous selection is retained.

下拉列表:

<select id="ThemeSelect">
    <option value="zelda">Zelda</option>
    <option value="smb2">SMB 2</option>
</select>

作为参考，此代码与 Wordpress 小部件中的一些 Javascript 一起更改了 css 代码，例如主题选择器.

For reference, this code is with some Javascript in a Wordpress widget that changes the css code, like a theme selector.

我如何将它保存为 cookie?我觉得我什么都试过了！

How would I make this save as a cookie? I feel like I've tried everything!

我应该说，但我使用此代码来更改 CSS:

I should have said, but I use this code to change the CSS:

var saveclass = null;
var sel = document.getElementById('ThemeSelect');
sel.onchange = function(){
    saveclass = saveclass ? saveclass : document.body.className;
    document.body.className = saveclass + ' ' + sel.value;
};

推荐答案

这些方面的东西应该适合你.通过javascript创建cookie的函数在从 JavaScript 设置 Cookie，javascripter.net 上的帖子.

Something along these lines should work for you. The function to create a cookie via javascript was found in Setting a Cookie from JavaScript, a post on javascripter.net.

HTML:

<select id="ThemeSelect" onchange="setCookie('theme', this.value, 365);">
    <option value="zelda">Zelda</option>
    <option value="smb2">SMB 2</option>
</select>

Javascript:

function setCookie(cookieName, cookieValue, nDays) {
    var today = new Date();
    var expire = new Date();

    if (!nDays) 
        nDays=1;

    expire.setTime(today.getTime() + 3600000*24*nDays);
    document.cookie = cookieName+"="+escape(cookieValue) + ";expires="+expire.toGMTString();
}

编辑:

保存 cookie

我已经为你将这两个功能合二为一了.

I have merged the two functions into one for you.

HTML:

<select id="ThemeSelect" onchange="saveTheme(this.value);">
    <option value="zelda">Zelda</option>
    <option value="smb2">SMB 2</option>
</select>

Javascript:

var saveclass = null;

function saveTheme(cookieValue)
{
    var sel = document.getElementById('ThemeSelect');

    saveclass = saveclass ? saveclass : document.body.className;
    document.body.className = saveclass + ' ' + sel.value;

    setCookie('theme', cookieValue, 365);
}

function setCookie(cookieName, cookieValue, nDays) {
    var today = new Date();
    var expire = new Date();

    if (nDays==null || nDays==0)
        nDays=1;

    expire.setTime(today.getTime() + 3600000*24*nDays);
    document.cookie = cookieName+"="+escape(cookieValue) + ";expires="+expire.toGMTString();
}

现场演示

返回页面时读取 cookie

感谢 dunsmoreb

Thanks to dunsmoreb

我们可以使用这个函数获取cookie，无耻地从这个问题中窃取.

We can get the cookie using this function, shamelessly stolen from this question.

function readCookie(name) {
  var nameEQ = name + "=";
  var ca = document.cookie.split(';');
  for(var i = 0; i < ca.length; i++) {
    var c = ca[i];
    while (c.charAt(0) == ' ') c = c.substring(1, c.length);
    if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length, c.length);
  }
  return null;
}

然后我们需要选择页面加载时的值.以下代码将完成此任务:

Then we need to select the value when the page loads. The following code will accomplish just that:

document.addEventListener('DOMContentLoaded', function() {
    var themeSelect = document.getElementById('ThemeSelect');
    var selectedTheme = readCookie('theme');

    themeSelect.value = selectedTheme;
    saveclass = saveclass ? saveclass : document.body.className;
    document.body.className = saveclass + ' ' + selectedTheme;
});

现场演示

这篇关于在 cookie 中保存下拉菜单选择?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！