md/assets/scripts/util.js

// 设置自定义颜色
function setColorWithTemplate(template) {
    return function (color) {
        let custom_theme = JSON.parse(JSON.stringify(template));
        custom_theme.block.h1['border-bottom'] = `2px solid ${color}`;
        custom_theme.block.h2['background'] = color;
        custom_theme.block.h3['border-left'] = `3px solid ${color}`;
        custom_theme.block.h4['color'] = color;
        custom_theme.inline.strong['color'] = color;
        return custom_theme;
    };
}


let setColorWithCustomTemplate = function setColorWithCustomTemplate(template, color) {
    let custom_theme = JSON.parse(JSON.stringify(template));
    custom_theme.block.h1['border-bottom'] = `2px solid ${color}`;
    custom_theme.block.h2['background'] = color;
    custom_theme.block.h3['border-left'] = `3px solid ${color}`;
    custom_theme.block.h4['color'] = color;
    custom_theme.inline.strong['color'] = color;
    return custom_theme;
}

// 设置自定义字体大小
function setFontSizeWithTemplate(template) {
    return function (fontSize) {
        let custom_theme = JSON.parse(JSON.stringify(template));
        custom_theme.block.h1['font-size'] = `${fontSize * 1.14}px`;
        custom_theme.block.h2['font-size'] = `${fontSize * 1.1}px`;
        custom_theme.block.h3['font-size'] = `${fontSize}px`;
        custom_theme.block.h4['font-size'] = `${fontSize}px`;
        return custom_theme;
    }
}

let setColor = setColorWithTemplate(default_theme);
let setFontSize = setFontSizeWithTemplate(default_theme);

function customCssWithTemplate(jsonString, color, theme) {
    let custom_theme = JSON.parse(JSON.stringify(theme));
    // block
    custom_theme.block.h1['border-bottom'] = `2px solid ${color}`;
    custom_theme.block.h2['background'] = color;
    custom_theme.block.h3['border-left'] = `3px solid ${color}`;
    custom_theme.block.h4['color'] = color;
    custom_theme.inline.strong['color'] = color;

    custom_theme.block.h1 = Object.assign(custom_theme.block.h1, jsonString.h1);
    custom_theme.block.h2 = Object.assign(custom_theme.block.h2, jsonString.h2);
    custom_theme.block.h3 = Object.assign(custom_theme.block.h3, jsonString.h3);
    custom_theme.block.h4 = Object.assign(custom_theme.block.h4, jsonString.h4);
    custom_theme.block.p = Object.assign(custom_theme.block.p, jsonString.p);
    custom_theme.block.blockquote = Object.assign(custom_theme.block.blockquote, jsonString.blockquote);
    custom_theme.block.blockquote_p = Object.assign(custom_theme.block.blockquote_p, jsonString.blockquote_p);
    custom_theme.block.image = Object.assign(custom_theme.block.image, jsonString.image);

    // inline
    custom_theme.inline.strong = Object.assign(custom_theme.inline.strong, jsonString.strong);
    custom_theme.inline.codespan = Object.assign(custom_theme.inline.codespan, jsonString.codespan);
    custom_theme.inline.link = Object.assign(custom_theme.inline.link, jsonString.link);
    custom_theme.inline.wx_link = Object.assign(custom_theme.inline.wx_link, jsonString.wx_link);

    return custom_theme;
}


/**
 * 将CSS形式的字符串转换为JSON
 * 
 * @param {css字符串} css 
 */
function css2json(css) {

    // 移除CSS所有注释
    while ((open = css.indexOf("/*")) !== -1 &&
        (close = css.indexOf("*/")) !== -1) {
        css = css.substring(0, open) + css.substring(close + 2);
    }

    // 初始化返回值
    let json = {};

    while (css.length > 0 && (css.indexOf('{') !== -1) && (css.indexOf('}') !== -1)) {
        // 存储第一个左/右花括号的下标
        const lbracket = css.indexOf('{');
        const rbracket = css.indexOf('}');

        // 第一步：将声明转换为Object，如：
        // `font: 'Times New Roman' 1em; color: #ff0000; margin-top: 1em;` 
        //  ==>
        // `{"font": "'Times New Roman' 1em", "color": "#ff0000", "margin-top": "1em"}`

        // 辅助方法：将array转为object
        function toObject(array) {
            let ret = {};
            array.forEach(e => {
                const index = e.indexOf(':');
                const property = e.substring(0, index).trim();
                const value = e.substring(index + 1).trim();
                ret[property] = value;
            });
            return ret;
        }

        // 切割声明块并移除空白符，然后放入数组中
        let declarations = css.substring(lbracket + 1, rbracket)
            .split(";")
            .map(e => e.trim())
            .filter(e => e.length > 0); // 移除所有""空值

        // 转为Object对象
        declarations = toObject(declarations);



        // 第二步：选择器处理，每个选择器会与它对应的声明相关联，如：
        // `h1, p#bar {color: red}`
        // ==>
        // {"h1": {color: red}, "p#bar": {color: red}}

        let selectors = css.substring(0, lbracket)
            // 以,切割，并移除空格：`"h1, p#bar, span.foo"` => ["h1", "p#bar", "span.foo"]
            .split(",")
            .map(selector => selector.trim());

        // 迭代赋值
        selectors.forEach(selector => {
            // 若不存在，则先初始化
            if (!json[selector]) json[selector] = {};
            // 赋值到JSON
            Object.keys(declarations).forEach(key => {
                json[selector][key] = declarations[key];
            });
        });

        // 继续下个声明块
        css = css.slice(rbracket + 1).trim();
    }

    // 返回JSON形式的结果串
    return json;
}