EnglishPal/app/static/js/highlight.js

let isHighlight = true;

function cancelBtnHandler() {
    cancelHighlighting();
    document.getElementById("text-content").removeEventListener("click", fillInWord, false);
    document.getElementById("text-content").removeEventListener("touchstart", fillInWord, false);
    document.getElementById("text-content").addEventListener("click", fillInWord2, false);
    document.getElementById("text-content").addEventListener("touchstart", fillInWord2, false);
}

function showBtnHandler() {
    document.getElementById("text-content").removeEventListener("click", fillInWord2, false);
    document.getElementById("text-content").removeEventListener("touchstart", fillInWord2, false);
    document.getElementById("text-content").addEventListener("click", fillInWord, false);
    document.getElementById("text-content").addEventListener("touchstart", fillInWord, false);
    highLight();
}

function getWord() {
    return window.getSelection ? window.getSelection() : document.selection.createRange().text;
}

function highLight() {
    if (!isHighlight) return;
    let articleContent = document.getElementById("article").innerText;
    let pickedWords = document.getElementById("selected-words");  // words picked to the text area
    let dictionaryWords = document.getElementById("selected-words2"); // words appearing in the user's new words list
    let allWords = dictionaryWords === null ? pickedWords.value + " " : pickedWords.value + " " + dictionaryWords.value;
    const list = allWords.split(" "); // 将所有的生词放入一个list中，用于后续处理
    for (let i = 0; i < list.length; ++i) {
        list[i] = list[i].replace(/(^\W*)|(\W*$)/g, ""); // 消除单词两边的非单词字符
        if (list[i] != "" && "<mark>".indexOf(list[i]) === -1 && "</mark>".indexOf(list[i]) === -1) {
            // 返回所有匹配单词的集合, 正则表达式RegExp()中, "\b"匹配一个单词的边界, g 表示全局匹配, i 表示对大小写不敏感。
            let matches = new Set(articleContent.match(new RegExp("\\b" + list[i] + "\\b", "gi")));
            for (let word of matches) {
                // 将文章中所有出现该单词word的地方改为："<mark>" + word + "<mark>"。 
                articleContent = articleContent.replace(new RegExp("\\b" + word + "\\b", "g"), "<mark>" + word + "</mark>");
            }
        }
    }
    document.getElementById("article").innerHTML = articleContent;
}

function cancelHighlighting() {
    let articleContent = document.getElementById("article").innerText;//将原来的.innerText改为.innerHtml，原因同上
    let pickedWords = document.getElementById("selected-words");
    const dictionaryWords = document.getElementById("selected-words2");    
    const list = pickedWords.value.split(" ");    
    if (pickedWords != null) {
        for (let i = 0; i < list.length; ++i) {
            list[i] = list[i].replace(/(^\s*)|(\s*$)/g, "");
            if (list[i] !== "") { //原来判断的代码中，替换的内容为“list[i]”这个字符串，这明显是错误的，我们需要替换的是list[i]里的内容
                articleContent = articleContent.replace(new RegExp("<mark>"+list[i]+"</mark>", "g"), list[i]);
            }
        }
    }
    if (dictionaryWords != null) {
        let list2 = pickedWords.value.split(" ");
        for (let i = 0; i < list2.length; ++i) {
            list2 = dictionaryWords.value.split(" ");
            list2[i] = list2[i].replace(/(^\s*)|(\s*$)/g, "");
            if (list2[i] !== "") { //原来代码中，替换的内容为“list[i]”这个字符串，这明显是错误的，我们需要替换的是list[i]里的内容
                articleContent = articleContent.replace(new RegExp("<mark>"+list2[i]+"</mark>", "g"), list2[i]);
            }
        }
    }
    document.getElementById("article").innerHTML = articleContent;
}

function fillInWord() {
    highLight();
}

function fillInWord2() {
    cancelHighlighting();
}

function toggleHighlighting() {
    if (isHighlight) {
        isHighlight = false;
        cancelHighlighting();
    } else {
        isHighlight = true;
        highLight();
    }
}

showBtnHandler();