diff --git a/package-lock.json b/package-lock.json
index f498dfa..3dbe169 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "vue-md",
-  "version": "1.4.4",
+  "version": "1.4.5",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index 311013f..229115f 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "vue-md",
-  "version": "1.4.4",
+  "version": "1.4.5",
   "homepage": ".",
   "description": "An open-source wechat markdown editor.",
   "author": "doocs",
diff --git a/src/assets/scripts/renderers/wx-renderer.js b/src/assets/scripts/renderers/wx-renderer.js
index f489d59..1e6d1e0 100644
--- a/src/assets/scripts/renderers/wx-renderer.js
+++ b/src/assets/scripts/renderers/wx-renderer.js
@@ -1,72 +1,73 @@
 import marked from "marked";
-const WxRenderer = function (opts) {
-    this.opts = opts;
-    let ENV_STRETCH_IMAGE = true;
+class WxRenderer {
+    constructor(opts) {
+        this.opts = opts;
+        let ENV_STRETCH_IMAGE = true;
 
-    let footnotes = [];
-    let footnoteIndex = 0;
-    let styleMapping = null;
+        let footnotes = [];
+        let footnoteIndex = 0;
+        let styleMapping = null;
 
-    const CODE_FONT_FAMILY =
-        "Menlo, Operator Mono, Consolas, Monaco, monospace";
+        const CODE_FONT_FAMILY =
+            "Menlo, Operator Mono, Consolas, Monaco, monospace";
 
-    let merge = (base, extend) => Object.assign({}, base, extend);
+        let merge = (base, extend) => Object.assign({}, base, extend);
 
-    this.buildTheme = (themeTpl) => {
-        let mapping = {};
-        let base = merge(themeTpl.BASE, {
-            "font-family": this.opts.fonts,
-            "font-size": this.opts.size,
-        });
-        let base_block = merge(base, {});
-        for (let ele in themeTpl.inline) {
-            if (themeTpl.inline.hasOwnProperty(ele)) {
-                let style = themeTpl.inline[ele];
-                mapping[ele] = merge(base, style);
-            }
-        }
-
-        for (let ele in themeTpl.block) {
-            if (themeTpl.block.hasOwnProperty(ele)) {
-                let style = themeTpl.block[ele];
-                if (ele === "code") {
-                    style["font-family"] = CODE_FONT_FAMILY;
+        this.buildTheme = (themeTpl) => {
+            let mapping = {};
+            let base = merge(themeTpl.BASE, {
+                "font-family": this.opts.fonts,
+                "font-size": this.opts.size,
+            });
+            let base_block = merge(base, {});
+            for (let ele in themeTpl.inline) {
+                if (themeTpl.inline.hasOwnProperty(ele)) {
+                    let style = themeTpl.inline[ele];
+                    mapping[ele] = merge(base, style);
                 }
-                mapping[ele] = merge(base_block, style);
             }
-        }
-        return mapping;
-    };
 
-    let getStyles = (tokenName, addition) => {
-        let arr = [];
-        let dict = styleMapping[tokenName];
-        if (!dict) return "";
-        for (const key in dict) {
-            arr.push(key + ":" + dict[key]);
-        }
-        return `style="${arr.join(";") + (addition || "")}"`;
-    };
-
-    let addFootnote = (title, link) => {
-        footnotes.push([++footnoteIndex, title, link]);
-        return footnoteIndex;
-    };
-
-    this.buildFootnotes = () => {
-        let footnoteArray = footnotes.map((x) => {
-            if (x[1] === x[2]) {
-                return `<code style="font-size: 90%; opacity: 0.6;">[${x[0]}]</code>: <i>${x[1]}</i><br/>`;
+            for (let ele in themeTpl.block) {
+                if (themeTpl.block.hasOwnProperty(ele)) {
+                    let style = themeTpl.block[ele];
+                    if (ele === "code") {
+                        style["font-family"] = CODE_FONT_FAMILY;
+                    }
+                    mapping[ele] = merge(base_block, style);
+                }
             }
-            return `<code style="font-size: 90%; opacity: 0.6;">[${x[0]}]</code> ${x[1]}: <i>${x[2]}</i><br/>`;
-        });
-        return `<h4 ${getStyles("h4")}>引用链接</h4><p ${getStyles(
-            "footnotes"
-        )}>${footnoteArray.join("\n")}</p>`;
-    };
+            return mapping;
+        };
 
-    this.buildAddition = () => {
-        return `
+        let getStyles = (tokenName, addition) => {
+            let arr = [];
+            let dict = styleMapping[tokenName];
+            if (!dict) return "";
+            for (const key in dict) {
+                arr.push(key + ":" + dict[key]);
+            }
+            return `style="${arr.join(";") + (addition || "")}"`;
+        };
+
+        let addFootnote = (title, link) => {
+            footnotes.push([++footnoteIndex, title, link]);
+            return footnoteIndex;
+        };
+
+        this.buildFootnotes = () => {
+            let footnoteArray = footnotes.map((x) => {
+                if (x[1] === x[2]) {
+                    return `<code style="font-size: 90%; opacity: 0.6;">[${x[0]}]</code>: <i>${x[1]}</i><br/>`;
+                }
+                return `<code style="font-size: 90%; opacity: 0.6;">[${x[0]}]</code> ${x[1]}: <i>${x[2]}</i><br/>`;
+            });
+            return `<h4 ${getStyles("h4")}>引用链接</h4><p ${getStyles(
+                "footnotes"
+            )}>${footnoteArray.join("\n")}</p>`;
+        };
+
+        this.buildAddition = () => {
+            return `
             <style>
             .preview-wrapper pre::before {
                 position: absolute;
@@ -82,128 +83,135 @@ const WxRenderer = function (opts) {
             }
             </style>
         `;
-    };
-
-    this.setOptions = (newOpts) => {
-        this.opts = merge(this.opts, newOpts);
-    };
-
-    this.hasFootnotes = () => footnotes.length !== 0;
-
-    this.getRenderer = (status) => {
-        footnotes = [];
-        footnoteIndex = 0;
-
-        styleMapping = this.buildTheme(this.opts.theme);
-        let renderer = new marked.Renderer();
-
-        renderer.heading = (text, level) => {
-            switch (level) {
-                case 1:
-                    return `<h1 ${getStyles("h1")}>${text}</h1>`;
-                case 2:
-                    return `<h2 ${getStyles("h2")}>${text}</h2>`;
-                case 3:
-                    return `<h3 ${getStyles("h3")}>${text}</h3>`;
-                default:
-                    return `<h4 ${getStyles("h4")}>${text}</h4>`;
-            }
-        };
-        renderer.paragraph = (text) => {
-            if (text.indexOf("<figure") != -1 && text.indexOf("<img") != -1) {
-                return text;
-            }
-            return text.replace(/ /g, "") === ""
-                ? ""
-                : `<p ${getStyles("p")}>${text}</p>`;
         };
 
-        renderer.blockquote = (text) => {
-            text = text.replace(/<p.*?>/g, `<p ${getStyles("blockquote_p")}>`);
-            return `<blockquote ${getStyles(
-                "blockquote"
-            )}>${text}</blockquote>`;
+        this.setOptions = (newOpts) => {
+            this.opts = merge(this.opts, newOpts);
         };
-        renderer.code = (text, lang) => {
-            text = text.replace(/</g, "&lt;").replace(/>/g, "&gt;");
-            const codeLines = text
-                .split("\n")
-                .map(
-                    (line) =>
-                        `<code class="prettyprint"><span class="code-snippet_outer">${
-                            line || "<br>"
-                        }</span></code>`
+
+        this.hasFootnotes = () => footnotes.length !== 0;
+
+        this.getRenderer = (status) => {
+            footnotes = [];
+            footnoteIndex = 0;
+
+            styleMapping = this.buildTheme(this.opts.theme);
+            let renderer = new marked.Renderer();
+
+            renderer.heading = (text, level) => {
+                switch (level) {
+                    case 1:
+                        return `<h1 ${getStyles("h1")}>${text}</h1>`;
+                    case 2:
+                        return `<h2 ${getStyles("h2")}>${text}</h2>`;
+                    case 3:
+                        return `<h3 ${getStyles("h3")}>${text}</h3>`;
+                    default:
+                        return `<h4 ${getStyles("h4")}>${text}</h4>`;
+                }
+            };
+            renderer.paragraph = (text) => {
+                if (
+                    text.indexOf("<figure") != -1 &&
+                    text.indexOf("<img") != -1
+                ) {
+                    return text;
+                }
+                return text.replace(/ /g, "") === ""
+                    ? ""
+                    : `<p ${getStyles("p")}>${text}</p>`;
+            };
+
+            renderer.blockquote = (text) => {
+                text = text.replace(
+                    /<p.*?>/g,
+                    `<p ${getStyles("blockquote_p")}>`
                 );
-            const codeTheme = "github";
-            return `
+                return `<blockquote ${getStyles(
+                    "blockquote"
+                )}>${text}</blockquote>`;
+            };
+            renderer.code = (text, lang) => {
+                text = text.replace(/</g, "&lt;").replace(/>/g, "&gt;");
+                const codeLines = text
+                    .split("\n")
+                    .map(
+                        (line) =>
+                            `<code class="prettyprint"><span class="code-snippet_outer">${
+                                line || "<br>"
+                            }</span></code>`
+                    );
+                const codeTheme = "github";
+                return `
                 <section class="code-snippet__${codeTheme}">
                     <pre class="code__pre" data-lang="${lang}">
                         ${codeLines.join("")}
                     </pre>
                 </section>
             `;
-        };
-        renderer.codespan = (text, lang) =>
-            `<code ${getStyles("codespan")}>${text}</code>`;
-        renderer.listitem = (text) =>
-            `<span ${getStyles(
-                "listitem"
-            )}><span style="margin-right: 10px;"><%s/></span>${text}</span>`;
+            };
+            renderer.codespan = (text, lang) =>
+                `<code ${getStyles("codespan")}>${text}</code>`;
+            renderer.listitem = (text) =>
+                `<span ${getStyles(
+                    "listitem"
+                )}><span style="margin-right: 10px;"><%s/></span>${text}</span>`;
 
-        renderer.list = (text, ordered, start) => {
-            text = text.replace(/<\/*p.*?>/g, "");
-            let segments = text.split(`<%s/>`);
-            if (!ordered) {
-                text = segments.join("•");
-                return `<p ${getStyles("ul")}>${text}</p>`;
-            }
-            text = segments[0];
-            for (let i = 1; i < segments.length; i++) {
-                text = text + i + "." + segments[i];
-            }
-            return `<p ${getStyles("ol")}>${text}</p>`;
+            renderer.list = (text, ordered, start) => {
+                text = text.replace(/<\/*p.*?>/g, "");
+                let segments = text.split(`<%s/>`);
+                if (!ordered) {
+                    text = segments.join("•");
+                    return `<p ${getStyles("ul")}>${text}</p>`;
+                }
+                text = segments[0];
+                for (let i = 1; i < segments.length; i++) {
+                    text = text + i + "." + segments[i];
+                }
+                return `<p ${getStyles("ol")}>${text}</p>`;
+            };
+            renderer.image = (href, title, text) => {
+                let subText = "";
+                if (text) {
+                    subText = `<figcaption ${getStyles(
+                        "figcaption"
+                    )}>${text}</figcaption>`;
+                }
+                let figureStyles = getStyles("figure");
+                let imgStyles = getStyles(
+                    ENV_STRETCH_IMAGE ? "image" : "image_org"
+                );
+                return `<figure ${figureStyles}><img ${imgStyles} src="${href}" title="${title}" alt="${text}"/>${subText}</figure>`;
+            };
+            renderer.link = (href, title, text) => {
+                if (href.indexOf("https://mp.weixin.qq.com") === 0) {
+                    return `<a href="${href}" title="${
+                        title || text
+                    }" ${getStyles("wx_link")}>${text}</a>`;
+                }
+                if (href === text || !status) {
+                    return text;
+                }
+                let ref = addFootnote(title || text, href);
+                return `<span ${getStyles(
+                    "link"
+                )}>${text}<sup>[${ref}]</sup></span>`;
+            };
+            renderer.strong = (text) =>
+                `<strong ${getStyles("strong")}>${text}</strong>`;
+            renderer.em = (text) =>
+                `<span style="font-style: italic;">${text}</span>`;
+            renderer.table = (header, body) =>
+                `<section style="padding:0 8px;"><table class="preview-table"><thead ${getStyles(
+                    "thead"
+                )}>${header}</thead><tbody>${body}</tbody></table></section>`;
+            // renderer.tablerow = (text) => `<tr style="">${text}</tr>`;
+            renderer.tablecell = (text, flags) =>
+                `<td ${getStyles("td")}>${text}</td>`;
+            renderer.hr = () =>
+                `<hr style="border-style: solid;border-width: 1px 0 0;border-color: rgba(0,0,0,0.1);-webkit-transform-origin: 0 0;-webkit-transform: scale(1, 0.5);transform-origin: 0 0;transform: scale(1, 0.5);">`;
+            return renderer;
         };
-        renderer.image = (href, title, text) => {
-            let subText = "";
-            if (text) {
-                subText = `<figcaption ${getStyles(
-                    "figcaption"
-                )}>${text}</figcaption>`;
-            }
-            let figureStyles = getStyles("figure");
-            let imgStyles = getStyles(
-                ENV_STRETCH_IMAGE ? "image" : "image_org"
-            );
-            return `<figure ${figureStyles}><img ${imgStyles} src="${href}" title="${title}" alt="${text}"/>${subText}</figure>`;
-        };
-        renderer.link = (href, title, text) => {
-            if (href.indexOf("https://mp.weixin.qq.com") === 0) {
-                return `<a href="${href}" title="${title || text}" ${getStyles(
-                    "wx_link"
-                )}>${text}</a>`;
-            }
-            if (href === text || !status) {
-                return text;
-            }
-            let ref = addFootnote(title || text, href);
-            return `<span ${getStyles(
-                "link"
-            )}>${text}<sup>[${ref}]</sup></span>`;
-        };
-        renderer.strong = (text) =>
-            `<strong ${getStyles("strong")}>${text}</strong>`;
-        renderer.em = (text) =>
-            `<span style="font-style: italic;">${text}</span>`;
-        renderer.table = (header, body) =>
-            `<section style="padding:0 8px;"><table class="preview-table"><thead ${getStyles(
-                "thead"
-            )}>${header}</thead><tbody>${body}</tbody></table></section>`;
-        // renderer.tablerow = (text) => `<tr style="">${text}</tr>`;
-        renderer.tablecell = (text, flags) =>
-            `<td ${getStyles("td")}>${text}</td>`;
-        renderer.hr = () =>
-            `<hr style="border-style: solid;border-width: 1px 0 0;border-color: rgba(0,0,0,0.1);-webkit-transform-origin: 0 0;-webkit-transform: scale(1, 0.5);transform-origin: 0 0;transform: scale(1, 0.5);">`;
-        return renderer;
-    };
-};
+    }
+}
 export default WxRenderer;