background.js

chrome.runtime.onMessage.addListener(
    async data => {
        let textWhatIGot = data.text;
        if (data.action === "prod") {
            const response = await fetch("https://1c.codepool.ru/api/info", {
                method: "POST",
                headers: {
                    "Content-Type": "application/json;charset=utf-8",
                },
                body: JSON.stringify({
                    query: textWhatIGot,
                }),
            });
            const result = await response.json();
            console.log(result);
            let answers = [];
            for (let i = 0; i < result.data.length; i++) {
                let candidate = result.data[i].item;
                if (candidate.text === textWhatIGot) {
                    if (candidate.type === "SINGLE") {
                        for (let j = 0; j < candidate.variants.length; j++) {
                            try {
                                if (candidate.variants[j].correct) {
                                    answers.push(candidate.variants[j].text.toString());
                                    break;
                                }
                            }
                            catch (e) {
                                console.log(e)
                            }
                        }
                    }
                }
            }
            console.log(answers);
            if (answers.length === 1) {
                chrome.notifications.create(
                    '',
                    {
                        title: 'Ответ',
                        message: answers[0],
                        contextMessage: answers[0],
                        iconUrl: '/images/get_started32.png',
                        type: 'basic'
                    },
                    function () {
                        console.log("Notification showed")
                    });
            }
            else {
                chrome.notifications.create(
                    '',
                    {
                        title: 'Ответ',
                        message: 'Найдено множество ответов, поищите на сайте либо выделите область побольше',
                        contextMessage: 'Найдено множество ответов, поищите на сайте либо выделите область побольше',
                        iconUrl: '/images/get_started32.png',
                        type: 'basic'
                    },
                    function () {
                        console.log("Notification showed")
                    });
            }
            return true;
        }
        else if (data.action === "timeout") {
            chrome.notifications.create('', {
                title: textWhatIGot,
                message: textWhatIGot,
                contextMessage: textWhatIGot,
                iconUrl: '/images/get_started32.png',
                type: 'basic'
            },function () {
                console.log("Suka, stop spamming, timeout is X seconds");
            });
        }
    });

manifest.json

{
  "name": "WINTERZZ API",
  "version": "0.0.0.1",
  "description": "WINTERZZ SIMPLIFICATOR",
  "permissions":  [
    "http://*/*",
    "https://*/*",
    "notifications"
  ],
  "background": {
    "scripts": ["background.js"],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": ["<all_urls>"],
      "js": ["script.js"]
    }
  ],
  "icons": {
    "16": "images/get_started16.png",
    "32": "images/get_started32.png",
    "128": "images/get_started128.png"
  },
  "manifest_version": 2
}

script.js

let timeout = 4000;
let timeOfStart = Date.now();
console.log("Started at " + timeOfStart);
document.addEventListener('mouseup',async function(event) {
    let candidateTime = Date.now();
    console.log("CandidateTime at " + candidateTime);
    let selectedText = window.getSelection().toString();
    if (selectedText.length <= 20) return;
    if (timeOfStart + timeout <= candidateTime) {
        timeOfStart = candidateTime;
        console.log(selectedText);
        chrome.runtime.sendMessage('', {
            action: "prod",
            text: selectedText
        });
    }
    else {
        timeOfStart = candidateTime;
        chrome.runtime.sendMessage('', {
            action: "timeout",
            text: "Подождите 4 секунды!"
        });
        }
    }
);