DeepL API—Office Add-in Starter Snippet

deepl-office.yaml.cpp

name: Blank snippet
description: Create a new snippet from a blank template.
host: WORD
api_set: {}
script:
  content: >
    /*
     MIT License

     Copyright 2022 DeepL SE (https://www.deepl.com)

     Permission is hereby granted, free of charge, to any person obtaining a copy
     of this software and associated documentation files (the "Software"), to deal
     in the Software without restriction, including without limitation the rights
     to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     copies of the Software, and to permit persons to whom the Software is
     furnished to do so, subject to the following conditions:

     The above copyright notice and this permission notice shall be included in all
     copies or substantial portions of the Software.

     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     SOFTWARE.
    */
    
    /*
     Thank you Marvin Becker (https://github.com/derwebcoder) for contributing this gist!
     
     Provide your API key here.
     You can find it here after logging in: https://www.deepl.com/account/summary
     If you need to create an API account, you can do so here: https://www.deepl.com/pro-api
     Don't forget to remove the key if you share your snippet with others.
    */

    const apiKey = "";


    /*
      ========================
      Section: HTML elements
      ========================
    */


    async function tryCatch(callback) {
      try {
        await callback();
      } catch (error) {
        console.error(error);
      }
    }


    const selectElements: Record<LanguageRequest["type"], HTMLSelectElement> = {
      source: document.querySelector("select#language-from"),
      target: document.querySelector("select#language-to")
    };

    const iframeElement: HTMLIFrameElement =
    document.querySelector("iframe#preview");


    /*
      ========================
      Section: Utilities
      ========================
    */


    /**
     * Load the supported languages, create an <option> element for each and append it to the corresponding <select> element that already exists in the HTML file
     */
    const hydrateLanguageDropdown = async (type: LanguageRequest["type"]) => {
      let languages = await fetchLanguages(type);

      // For each language create an <option> element
      languages.forEach((lang) => {
        const option = document.createElement("option");
        option.setAttribute("value", lang.language);
        option.innerHTML = lang.name;
        selectElements[type].append(option);
      });

      // For convenience set the target language to the interface language
      if (type === "target") {
        setDefaultTargetLanguage(languages);
      }
    };


    /**
     * For convenience we can set the target language automatically to the users interface language.
     * If we don't support a matching language we just default to the first of the list.
     */
    const setDefaultTargetLanguage = (languages: LanguagesResponse) => {
      const interfaceLanguage = Office.context.displayLanguage.toUpperCase();
      if (languages.find((l) => l.language === interfaceLanguage)) {
        selectElements["target"].value = interfaceLanguage;
      } else {
        selectElements["target"].value = languages[0].language;
      }
    };


    /**
     * For some reason Office adds control characters to the string. We have to remove them otherwise they would end up in the translation.
     */
    const cleanOfficeHTML = (htmlString: string) => {
      return htmlString.replace(/[\u0000-\u001F\u007F-\u009F]/g, " ");
    };


    /*
      ========================
      Section: DeepL API
      ========================
    */


    /**
     * Fetching the list of supported languages.
     * * @see https://www.deepl.com/docs-api/general/get-languages/
     */
    const fetchLanguages = async (type: LanguageRequest["type"]):
    Promise<LanguagesResponse> => {
      try {
        const response = await fetch(`https://api.deepl.com/v2/languages?auth_key=${apiKey}`, {
          method: "POST",
          headers: {
            Accept: "*/*",
            "Content-Type": "application/x-www-form-urlencoded"
          },
          body: `auth_key=${apiKey}&type=${type}`
        });

        if (!response.ok) {
          if (response.status === 403) {
            throw new Error("Your API key is invalid. Try another one.");
          }
          throw new Error(
            `API returned error code ${response.status}. See https://www.deepl.com/docs-api/api-access/error-handling/.`
          );
        }

        return await response.json();
      } catch (e) {
        throw new Error(`Fetching languages failed. ${e}`);
      }
    };


    /**
     * Fetching the translation for a given HTML input and languages.
     * @see https://www.deepl.com/docs-api/translate-text/translate-text/
     */
    const fetchTranslation = async (text: string, targetLang: string,
    sourceLang?: string): Promise<string> => {
      try {
        const response = await fetch(`https://api.deepl.com/v2/translate?auth_key=${apiKey}`, {
          method: "POST",
          headers: {
            Accept: "*/*",
            "Content-Type": "application/x-www-form-urlencoded"
          },
          body: `auth_key=${apiKey}&text=${encodeURIComponent(text)}&source_lang=${encodeURIComponent(
            sourceLang
          )}&target_lang=${encodeURIComponent(targetLang)}&tag_handling=html` // we want to handle HTML
        });

        const result: TranslationReponse = await response.json();
        return result.translations[0].text;
      } catch (e) {
        throw new Error("Fetching translation failed");
      }
    };


    /*
      ========================
      Section: TypeScript types
      ========================

      Some simple TypeScript types for convenience

      These are not complete and stripped to our use case
    */


    type LanguageRequest = {
      type: "source" | "target";
    };


    type LanguagesResponse = Array<{
      language: string;
      name: string;
    }>;


    type TranslationReponse = {
      translations: Array<{
        text: string;
      }>;
    };


    /*
      ========================
      Section: Main
      ========================
    */


    Office.onReady((info) => {
      // First we want to hydrate our view
      tryCatch(async () => {
        await hydrateLanguageDropdown("source");
        await hydrateLanguageDropdown("target");
      });

      Word.run(async (context) => {
        // Add an event listener for when the user selects something
        Office.context.document.addHandlerAsync(Office.EventType.DocumentSelectionChanged, () => {
          // Get the selected text (in HTML format)
          Office.context.document.getSelectedDataAsync<string>(Office.CoercionType.Html, (asyncResult) => {
            tryCatch(async () => {
              iframeElement.setAttribute("srcdoc", "loading ...");

              // if receiving the selected text failed for some reason stop right here
              if (asyncResult.status === Office.AsyncResultStatus.Failed) {
                iframeElement.setAttribute("srcdoc", "Getting the selected text failed.");
                throw new Error("Action failed. Error: " + asyncResult.error.message);
              }

              const cleanedHTML = cleanOfficeHTML(asyncResult.value);

              try {
                // load the translation for the selected text
                // note that in the fetchTranslation function we have set the API parameter of `tag_handling` to `html`
                const translation = await fetchTranslation(
                  cleanedHTML,
                  selectElements["target"].value,
                  selectElements["source"].value
                );

                // set the iframe content with the translation
                iframeElement.setAttribute("srcdoc", translation);
              } catch (e) {
                // if something fails show an error message
                iframeElement.setAttribute("srcdoc", e);
              }
            });
          });
        });
      });
    });
  language: typescript
template:
  content: "<section>\n\t<div id=\"languages\">\n\t\t<select id=\"language-from\">\n            <option value=\"\">(automatic)</option>\n        </select>\n\t\t<span>&gt;</span>\n\t\t<select id=\"language-to\">\n        </select>\n\t</div>\n\n\t<iframe id=\"preview\"></iframe>\n</section>"
  language: html
style:
  content: |-
    html, body {
        margin: 0;
        padding: 0;
        background: #ececec;
    }

    section {
        display: grid;
        grid-template-rows: 32px 1fr;
        gap: 8px;
        height: 100vh;
        align-items: center;
        padding: 12px;
        box-sizing: border-box;
    }

    #languages {
        display: grid;
        grid-template-columns: 1fr 24px 1fr;
    }

    #languages span {
        text-align: center;
    }

    iframe {
        height: 100%;
        width: 100%;
        background: white;
        border: 1px solid #c6c6c6;
        padding: 0 10px;
        box-sizing: border-box;
    }
  language: css
libraries: |
  https://appsforoffice.microsoft.com/lib/1/hosted/office.js
  @types/office-js

If using a free API, the code needs to replace 'https://api.deepl.com/v2/' with 'https://api-free.deepl.com/v2/'.
The improved code can be found in:https://gist.github.com/shaoshuai6666/ff18fc1fa7e5bb771de047e3356cf868