HTML document, ASCII text
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<!DOCTYPE html>
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<html data-theme="light">
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<head>
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<style type="text/css">
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html[data-theme=light] {
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background: #fff;
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color: #000;
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--buttonBackground: #fefefe;
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--buttonBorder: #ccc;
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--buttonColor: #001;
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}
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html[data-theme=dark] {
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background: #000;
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color: #fff;
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--buttonBackground: #101010;
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--buttonBorder: #333;
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--buttonColor: #fff;
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}
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html[data-theme=hotdogstand] {
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background: #f00;
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color: #fff;
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--buttonBackground: #ff0;
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--buttonBorder: #000;
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--buttonColor: #000;
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}
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button {
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background: var(--buttonBackground);
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border: var(--buttonBorder) solid 3px;
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color: var(--buttonColor);
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}
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</style>
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</head>
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<body>
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<button id="theme-switch">Switch Theme</button>
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This is epic!
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<script type="text/javascript">
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const themes = ["light", "dark", "hotdogstand"];
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const ThemeSwitchButton = document.querySelector("#theme-switch");
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const HTML = document.documentElement;
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ThemeSwitchButton.addEventListener("click", SwitchTheme);
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function SwitchTheme() {
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let CurrentTheme = themes.indexOf(HTML.dataset.theme); // Gets how far in the current theme is into the "themes" constant.
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if (CurrentTheme + 1 >= themes.length) { // Checks if it's at the end of the array,
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HTML.dataset.theme = themes[0]; // If so, reset at the start.
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return; // Ends the function here, preventing next bit of code from running.
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}
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HTML.dataset.theme = themes[CurrentTheme + 1]; // Goes to the next theme.
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}
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</script>
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</body>
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</html>
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