这是使用 localStorage 的正确方法吗？

Question

I want to be able to switch themes using a element. The themes are stored in different.css files and by picking a different <option> , I can in turn pick a different theme. However, switching pages switches themes back to whatever I have currently written into my actual template. Here is my.js file:

$(function() {
    var theme = $("#theme");
    var getTheme = localStorage.getItem("theme");
    
    
    $("#select option:selected").each(function() { /* Switch on-change function */
        if (getTheme == $(this).data("theme")) {
            theme.attr("href", getTheme); /* Set the theme of the page to whatever theme applies to this option */
            console.log($(this).data("theme"));
        }
        else {
            theme.attr("href", $(this).data("theme"));
            localStorage.setItem("theme", $(this).data("theme")); /* Store the choice into local storage; should persist upon page reload */
            console.log($(this).data("theme"));
        }
    });
});

And here is my template:

<div style="text-align: center">
  <select class="form-control" name="select" id="select">
      <option selected value="original" data-theme="/static/styles.css">Original</option>
      <option value="darkmode" data-theme="/static/stylesdark.css">Dark Mode</option>
      <option value="cybermode" data-theme="/static/stylescyber.css">Cyber Mode</option>
      <option value="fire" data-theme="/static/stylesfire.css">Fire & Brimstone</option>
  </select>
</div>

I figure my error has something to do with how my use of localStorage is being handled, but I'm not sure how.

Answer 1

You code seems [for me] very complicated

just do

<div style="text-align: center">
  <select class="form-control" name="select" id="select">
    <option value="/static/styles.css"     > Original      </option>
    <option value="/static/stylesdark.css" > Dark Mode      </option>
    <option value="/static/stylescyber.css"> Cyber Mode      </option>
    <option value="/static/stylesfire.css" > Fire & Brimstone </option>
  </select>
</div>

const theSelect = document.querySelector('#select')

theSelect.value = localStorage.getItem('theme') || theSelect.options[0].value 

theSelect.onchange = e =>
  {
  localStorage.setItem('theme', theSelect.value)
  }

Answer 2

Your code is a lot more complicated than it needs to be

$(function() {

  var theme = $("#theme");
  var select = $("#select");

  function setStyleSheet(selectOption) {
    // use local storage, if no value, use default
    var themeHref = localStorage.getItem("theme") || "/your/default.css";
    // update the stylesheet
    theme.attr("href", themeHref);
    // if we need to, update the option with the value from local storage
    if (selectOption) {
      select.find('option[data-value="' + themeHref + '"]').prop('selected', true);
    }
  }

  // bind change event to the select
  select.on('change', function() {
    // grab selected option
    var theme = select.find("option:selected").data("theme");
    // update local storage
    localStorage.setItem("theme", theme);
    // update the style sheeet
    setStyleSheet(false);
  });

  // update the stylesheet on page load
  setStyleSheet(true);

});

If you used the value instead of data attributes this would be even simpler.

 $(function() { var theme = $("#theme"); var select = $("#select"); function setStyleSheet(selectOption) { // use local storage, if no value, use default var themeHref = localStorage.getItem("theme") || "/your/default.css"; // update the stylesheet theme.attr("href", themeHref); // if we need to, update the option with the value from local storage if (selectOption) { select[0].value = themeHref; } } // bind change event to the select select.on('change', function() { // grab selected option's value var theme = this.value; // update local storage localStorage.setItem("theme", theme); // update the style sheeet setStyleSheet(false); }); // update the stylesheet on page load setStyleSheet(true); });