diff --git a/CHANGELOG.md b/CHANGELOG.md
index a62cd4ea..f9c17529 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 English | [简体中文](./CHANGELOG_CN.md)
 
+## 3.12.1 (2022-02-25)
+
+- `Fix(Core)` Fix bug that `VConsole.instance` is empty when VConsole `import` as a new module.
+- `Chore(Core)` Fix type declaration errors caused by vendors.
+
+
 ## 3.12.0 (2022-02-17)
 
 - `Feat(Core)` Add new static property `VConsole.instance` to get the singleton instance.
diff --git a/CHANGELOG_CN.md b/CHANGELOG_CN.md
index 6979cf06..ce50f159 100644
--- a/CHANGELOG_CN.md
+++ b/CHANGELOG_CN.md
@@ -1,5 +1,11 @@
 [English](./CHANGELOG.md) | 简体中文
 
+## 3.12.1 (2022-02-25)
+
+- `Fix(Core)` 修复当 VConsole 作为新模块 `import` 时 `VConsole.instance` 为空的问题。
+- `Chore(Core)` 修复由外部依赖库引起的 TypeScript 类型声明错误问题。
+
+
 ## 3.12.0 (2022-02-17)
 
 - `Feat(Core)` 新增静态属性 `VConsole.instance` 以获取实例化后的单例 vConsole 对象。
diff --git a/build/build.typings.js b/build/build.typings.js
new file mode 100644
index 00000000..69861e29
--- /dev/null
+++ b/build/build.typings.js
@@ -0,0 +1,21 @@
+const fs = require('fs');
+const { execSync } = require('child_process');
+const vendorConfig = require('./vendor.json');
+
+const main = () => {
+  console.group('\nEmitting type declarations...');
+  const distFile = './dist/vconsole.min.d.ts';
+  if (fs.existsSync(distFile)) {
+    fs.unlinkSync(distFile);
+  }
+  execSync('tsc --build ./tsconfig.type.json');
+  let distContent = fs.readFileSync(distFile, 'utf8');
+  for (const name of vendorConfig.name) {
+    distContent = distContent.replace(new RegExp(`['"]${name}['"]`, 'g'), `"vendor/${name}"`);
+  }
+  const vendorContent = '/// <reference path="../build/vendor.d.ts" />\n\n';
+  fs.writeFileSync(distFile, vendorContent + distContent, 'utf8');
+  console.groupEnd();
+};
+
+main();
\ No newline at end of file
diff --git a/build/vendor.d.ts b/build/vendor.d.ts
new file mode 100644
index 00000000..9b948616
--- /dev/null
+++ b/build/vendor.d.ts
@@ -0,0 +1,24 @@
+declare module 'vendor/core-js/stable/symbol' {
+}
+
+declare module 'vendor/mutation-observer' {
+  export class MutationObserver {
+  }
+}
+
+declare module 'vendor/svelte' {
+  export class SvelteComponent {
+  }
+}
+
+declare module 'vendor/svelte/store' {
+  export interface Subscriber<T> {
+  }
+  export interface Unsubscriber {
+  }
+  export interface Updater<T> {
+  }
+  export interface Writable<T> {
+  }
+}
+
diff --git a/build/vendor.json b/build/vendor.json
new file mode 100644
index 00000000..96afe665
--- /dev/null
+++ b/build/vendor.json
@@ -0,0 +1,8 @@
+{
+  "name": [
+    "core-js/stable/symbol",
+    "mutation-observer",
+    "svelte/store",
+    "svelte"
+  ]
+}
\ No newline at end of file
diff --git a/package.json b/package.json
index 17eb2ece..7056e8cf 100644
--- a/package.json
+++ b/package.json
@@ -1,10 +1,11 @@
 {
   "name": "vconsole",
-  "version": "3.12.0",
+  "version": "3.12.1",
   "description": "A lightweight, extendable front-end developer tool for mobile web page.",
   "homepage": "https://github.com/Tencent/vConsole",
   "files": [
     "dist/*",
+    "build/vendor.d.ts",
     "CHANGELOG*",
     "README*"
   ],
@@ -12,7 +13,7 @@
   "typings": "dist/vconsole.min.d.ts",
   "scripts": {
     "build": "webpack --mode=production --progress",
-    "build:typings": "tsc --build tsconfig.type.json",
+    "build:typings": "node ./build/build.typings.js",
     "build:dev": "webpack --mode=development --progress",
     "watch": "webpack --mode=development --watch --progress",
     "serve": "webpack serve --config webpack.serve.config --progress",
diff --git a/src/core/core.ts b/src/core/core.ts
index 3b1a7a52..9e18fcdb 100644
--- a/src/core/core.ts
+++ b/src/core/core.ts
@@ -53,9 +53,6 @@ export class VConsole {
   public system: VConsoleLogExporter;
   public network: VConsoleNetworkExporter;
 
-  // Singleton instance
-  public static instance: VConsole;
-
   // Export static classes
   public static VConsolePlugin = VConsolePlugin;
   public static VConsoleLogPlugin = VConsoleLogPlugin;
@@ -71,7 +68,6 @@ export class VConsole {
       return VConsole.instance;
     }
 
-    VConsole.instance = this;
     this.isInited = false;
     this.option = {
       defaultPlugins: ['system', 'network', 'element', 'storage'],
@@ -132,6 +128,29 @@ export class VConsole {
     }
   }
 
+  /**
+   * Get singleton instance.
+   **/
+  public static get instance() {
+    return (<any>$.one(VCONSOLE_ID))?.__VCONSOLE_INSTANCE as VConsole;
+  }
+
+  /**
+   * Set singleton instance.
+   **/
+  public static set instance(value: VConsole | undefined) {
+    if (value !== undefined && !(value instanceof VConsole)) {
+      console.debug('[vConsole] Cannot set `VConsole.instance` because the value is not the instance of VConsole.');
+      return;
+    }
+    const $elm = $.one(VCONSOLE_ID);
+    if ($elm) {
+      (<any>$elm).__VCONSOLE_INSTANCE = value;
+    } else {
+      console.debug('[vConsole] Cannot set `VConsole.instance` because vConsole has not finished initializing yet.');
+    }
+  }
+
   /**
    * Add built-in plugins.
    */
@@ -199,6 +218,9 @@ export class VConsole {
         const pluginId = e.detail.pluginId;
         this.showPlugin(pluginId);
       });
+
+      // bind vConsole instance
+      VConsole.instance = this;
     }
 
     // set options into component
@@ -497,6 +519,10 @@ export class VConsole {
     if (!this.isInited) {
       return;
     }
+    // reverse isInited when destroyed
+    this.isInited = false;
+    VConsole.instance = undefined;
+
     // remove plugins
     const pluginIds = Object.keys(this.pluginList);
     for (let i = pluginIds.length - 1; i >= 0; i--) {
@@ -504,10 +530,6 @@ export class VConsole {
     }
     // remove component
     this.compInstance.$destroy();
-
-    // reverse isInited when destroyed
-    this.isInited = false;
-    VConsole.instance = undefined;
   }
 
 } // END class
diff --git a/src/lib/mito.ts b/src/lib/mito.ts
deleted file mode 100644
index 2db4f418..00000000
--- a/src/lib/mito.ts
+++ /dev/null
@@ -1,117 +0,0 @@
-/**
- * Mito.js
- * A simple template engine
- *
- * @author Maiz
- */
-
-export default class Mito {
-  /**
-   * Render `tpl` with `data` into a HTML string.
-   */
-  public render<T extends true>(tpl: string, data: any, toString: T): string;
-  /**
-   * Render `tpl` with `data` into a HTML element.
-   */
-  public render<T extends false>(tpl: string, data: any, toString?: T): Element;
-  public render<T extends boolean>(tpl: string, data: any, toString?: T) {
-    const pattern = /\{\{([^\}]+)\}\}/g;
-    let code = '';
-    let codeWrap = '';
-    let pointer = 0;
-    let match: RegExpExecArray;
-    const RenderFunction = {
-      // Escape HTML to XSS-safe text
-      text: (text: string | number) => {
-        if (typeof text !== 'string' && typeof text !== 'number') { return text; }
-        return String(text).replace(/[<>&" ]/g, (c) => {
-          return { '<': '&lt;', '>': '&gt;', '&': '&amp;', '"': '&quot;', ' ': '&nbsp;' }[c];
-        });
-      },
-      // Change invisible characters to visible characters
-      visibleText: (text: string) => {
-        if (typeof text !== 'string') { return text; }
-        return String(text).replace(/[\n\t]/g, (c) => {
-          return { '\n': '\\n', '\t': '\\t' }[c];
-        });
-      },
-    };
-    const addCode = (line: string, isJS: boolean) => {
-      if (line === '') { return; }
-      // console.log(line)
-      if (isJS) {
-        if ( line.match(/^ ?else/g) ) {
-          // else  --> } else {
-          code += '} ' + line + ' {\n';
-        } else if ( line.match(/\/(if|for|switch)/g) ) {
-          // /if  -->  }
-          code += '}\n';
-        } else if ( line.match(/^ ?if|for|switch/g) ) {
-          // if (age)  -->  if (this.age) {
-          code += line + ' {\n';
-        } else if ( line.match(/^ ?(break|continue) ?$/g) ) {
-          // break --> break;
-          code += line + ';\n';
-        } else if ( line.match(/^ ?(case|default)/g) ) {
-          // case (1) --> case (1):
-          code += line + ':\n';
-        } else {
-          // name  -->  name
-          code += 'arr.push(String('+ line +'));\n';
-        }
-      } else {
-        // plain text
-        code += 'arr.push("' + line.replace(/"/g, '\\"' )+ '");\n';
-      }
-    };
-    // init global param
-    (<any>window).__mito_data = data;
-    (<any>window).__mito_code = "";
-    (<any>window).__mito_result = "";
-    // remove spaces after switch
-    tpl = tpl.replace(/(\{\{ ?switch(.+?)\}\})[\r\n\t ]+\{\{/g, '$1{{');
-    // line breaks
-    tpl = tpl.replace(/^[\r\n]/, '').replace(/\n/g, '\\\n').replace(/\r/g, '\\\r');
-    // init code
-    codeWrap = '(function(){\n';
-    code = 'var arr = [];\n';
-    // renderFunctions
-    for (let fn in RenderFunction) {
-      code += `var ${fn} = ${RenderFunction[fn].toString()};\n`;
-    }
-    while (match = pattern.exec(tpl)) {
-      addCode( tpl.slice(pointer, match.index), false );
-      addCode( match[1], true );
-      pointer = match.index + match[0].length;
-    }
-    addCode( tpl.substr(pointer, tpl.length - pointer), false );
-    code += '__mito_result = arr.join("");';
-    code = 'with (__mito_data) {\n' + code + '\n}';
-    codeWrap += code;
-    codeWrap += '})();';
-    // console.log("code:\n"+codeWrap);
-    // run code, do NOT use `eval` or `new Function` to avoid `unsafe-eval` CSP rule
-    const scriptList = document.getElementsByTagName('script');
-    let nonce = '';
-    // find the first script with nonce
-    for (let i = 0; i < scriptList.length; i++) {
-      if (scriptList[i].nonce) {
-        nonce = scriptList[i].nonce
-        break
-      }
-    }
-    
-    const script = document.createElement('SCRIPT');
-    script.innerHTML = codeWrap;
-    script.setAttribute('nonce', nonce);
-    document.documentElement.appendChild(script);
-    const domString = (<any>window).__mito_result;
-    document.documentElement.removeChild(script);
-    if (!toString) {
-      const e = document.createElement('DIV');
-      e.innerHTML = domString;
-      return e.children[0];
-    }
-    return domString;
-  }
-}
diff --git a/tsconfig.json b/tsconfig.json
index 3fd7d99c..f831bdfd 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -16,5 +16,5 @@
 		},
 	},
   "include": ["src/**/*"],
-	"exclude": ["node_modules/*"],
+	"exclude": ["build/vendor.d.ts", "node_modules/*"],
 }
\ No newline at end of file
diff --git a/tsconfig.type.json b/tsconfig.type.json
index 40bbddfe..ddb39251 100644
--- a/tsconfig.type.json
+++ b/tsconfig.type.json
@@ -4,7 +4,7 @@
     "declaration": true,
     // "declarationDir": "./dist/typings",
     "outFile": "dist/vconsole.min.d.ts",
-    "outDir": "./dist/typings",
+    "outDir": "./dist",
     "baseUrl": "./src",
     "rootDir": "./src",
     "moduleResolution": "node",
diff --git a/webpack.config.js b/webpack.config.js
index 5998325c..3422f54f 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -131,9 +131,7 @@ module.exports = (env, argv) => {
         apply: (compiler) => {
           compiler.hooks.done.tap('DeclarationEmitter', () => {
             if (isDev) return; // only emit declarations in prod mode
-            console.group('Emitting type declarations...');
             execSync('npm run build:typings');
-            console.groupEnd();
           });
         },
       },