test.html

<div id="translate_tools">
  <span id="google_translate_element"></span>
  <br />
  <span id="google_translate_element_neg"></span>
  <br />
  <button onclick="jp2en()">jp2en</button>
  <br />
  <textarea
    id="other_language_prompt"
    data-testid="textbox"
    class="scroll-hide block gr-box gr-input w-full gr-text-input"
    placeholder="In put Prompt here to translate"
    rows="2"
    style="overflow-y: scroll; height: 63px"
    spellcheck="false"
  ></textarea>
  <br />
  <textarea
    id="other_language_neg_prompt"
    data-testid="textbox"
    class="scroll-hide block gr-box gr-input w-full gr-text-input"
    placeholder="In put Negative Prompt here to translate"
    rows="2"
    style="overflow-y: scroll; height: 63px"
    spellcheck="false"
  ></textarea>
</div>
<div
  id="txt2img_prompt"
  class="gr-block gr-box relative w-full overflow-hidden border-solid border border-gray-200 gr-padded"
>
  <div class="wrap svelte-1ka70lm opacity-0"></div>
  <label class="block w-full"
    ><span
      class="text-gray-500 text-[0.855rem] mb-2 block dark:text-gray-200 relative z-40 sr-only h-0 !m-0"
      >Prompt</span
    >
    <textarea
      data-testid="textbox"
      class="scroll-hide block gr-box gr-input w-full gr-text-input"
      placeholder="Prompt (press Ctrl+Enter or Alt+Enter to generate)"
      rows="2"
      style="overflow-y: scroll; height: 63px"
      spellcheck="false"
    ></textarea>
  </label>
</div>
<button onclick="en2jp()">en2jp</button>
<script>
  let isTranslateEnable = false;

  // observer for user using google translate
  new MutationObserver(function () {
    isTranslateEnable = false;
    document.querySelector("#translate_tools").style.display = "none";

    if (document.documentElement.className.match("translated")) {
      isTranslateEnable = true;
      document.querySelector("#translate_tools").style.display = "block";
    }
  }).observe(document.documentElement, {
    attributes: true,
    attributeFilter: ["class"],
    childList: false,
    characterData: false,
  });

  txt2img_textarea = document
    .evaluate(
      '//*[@id="txt2img_prompt"]/label/textarea',
      document,
      null,
      XPathResult.ANY_TYPE,
      null
    )
    .iterateNext();
  txt2img_textarea.addEventListener("input", () => {
    if (isTranslateEnable) {
      document.querySelector("#google_translate_element").textContent =
        "✔️" + txt2img_textarea.value.replaceAll("_", " ");
      setTimeout(function () {
        document.querySelector("#other_language_prompt").value = document
          .querySelector("#google_translate_element")
          .textContent.replace("✔️", "");
      }, 500);
    }
  });

  document
    .querySelector("#other_language_prompt")
    ?.addEventListener("input", () => {
      if (isTranslateEnable) {
        const translatedText = document.querySelector(
          "#other_language_prompt"
        ).value;
        document.querySelector("#google_translate_element").textContent =
          "✔️" + translatedText;
        setTimeout(function () {
          txt2img_textarea.value = document
            .querySelector("#google_translate_element")
            .textContent.replace("✔️", "");
        }, 500);
      }
    });

  let google_iframe;

  function jp2en() {
    if (isTranslateEnable) {
      google_iframe = document
        .evaluate(
          '//*[@id=":1.container"]',
          document,
          null,
          XPathResult.ANY_TYPE,
          null
        )
        .iterateNext().contentDocument;

      const close = google_iframe
        ?.evaluate(
          '//*[@id=":1.close"]',
          google_iframe,
          null,
          XPathResult.ANY_TYPE,
          null
        )
        .iterateNext();
      close.click();
    }

    getScript("https://translate.google.com/translate_a/element.js", () => {
      setTimeout(() => {
        new google.translate.TranslateElement(
          {
            pageLanguage: "ja",
            // autoDisplay: false,
          },
          "google_translate_element"
        );

        doGTranslate("ja|en");
      }, 1000);
    });
  }

  function en2jp() {
    if (isTranslateEnable) {
      google_iframe = document
        .evaluate(
          '//*[@id=":1.container"]',
          document,
          null,
          XPathResult.ANY_TYPE,
          null
        )
        .iterateNext().contentDocument;

      const close = google_iframe
        ?.evaluate(
          '//*[@id=":1.close"]',
          google_iframe,
          null,
          XPathResult.ANY_TYPE,
          null
        )
        .iterateNext();
      close.click();
    }

    getScript("https://translate.google.com/translate_a/element.js", () => {
      setTimeout(() => {
        new google.translate.TranslateElement(
          {
            pageLanguage: "en",
            // autoDisplay: false,
          },
          "google_translate_element"
        );

        doGTranslate("en|ja");
      }, 1000);
    });
  }
</script>
<script>
  function getScript(source, callback) {
    var script = document.createElement("script");
    var prior = document.getElementsByTagName("script")[0];
    script.async = 1;

    script.onload = script.onreadystatechange = function (_, isAbort) {
      if (
        isAbort ||
        !script.readyState ||
        /loaded|complete/.test(script.readyState)
      ) {
        script.onload = script.onreadystatechange = null;
        script = undefined;

        if (!isAbort && callback) setTimeout(callback, 0);
      }
    };

    script.src = source;
    prior.parentNode.insertBefore(script, prior);
  }
</script>
<script type="text/javascript">
  /* <![CDATA[ */
  eval(
    (function (p, a, c, k, e, r) {
      e = function (c) {
        return (
          (c < a ? "" : e(parseInt(c / a))) +
          ((c = c % a) > 35 ? String.fromCharCode(c + 29) : c.toString(36))
        );
      };
      if (!"".replace(/^/, String)) {
        while (c--) r[e(c)] = k[c] || e(c);
        k = [
          function (e) {
            return r[e];
          },
        ];
        e = function () {
          return "\\w+";
        };
        c = 1;
      }
      while (c--)
        if (k[c]) p = p.replace(new RegExp("\\b" + e(c) + "\\b", "g"), k[c]);
      return p;
    })(
      "6 7(a,b){n{4(2.9){3 c=2.9(\"o\");c.p(b,f,f);a.q(c)}g{3 c=2.r();a.s('t'+b,c)}}u(e){}}6 h(a){4(a.8)a=a.8;4(a=='')v;3 b=a.w('|')[1];3 c;3 d=2.x('y');z(3 i=0;i<d.5;i++)4(d[i].A=='B-C-D')c=d[i];4(2.j('k')==E||2.j('k').l.5==0||c.5==0||c.l.5==0){F(6(){h(a)},G)}g{c.8=b;7(c,'m');7(c,'m')}}",
      43,
      43,
      "||document|var|if|length|function|GTranslateFireEvent|value|createEvent||||||true|else|doGTranslate||getElementById|google_translate_element|innerHTML|change|try|HTMLEvents|initEvent|dispatchEvent|createEventObject|fireEvent|on|catch|return|split|getElementsByTagName|select|for|className|goog|te|combo|null|setTimeout|500".split(
        "|"
      ),
      0,
      {}
    )
  );
  /* ]]> */
</script>