diff --git a/demo/template/README.md b/demo/template/README.md
new file mode 100644
index 000000000..d70afb158
--- /dev/null
+++ b/demo/template/README.md
@@ -0,0 +1,9 @@
+# LiquidJS for Node.js
+
+## Get Started
+
+```bash
+cd demo/nodejs
+npm install
+npm start
+```
\ No newline at end of file
diff --git a/demo/template/get-outputs.ts b/demo/template/get-outputs.ts
new file mode 100644
index 000000000..ca61dc521
--- /dev/null
+++ b/demo/template/get-outputs.ts
@@ -0,0 +1,25 @@
+import { Output, Template, Tag } from 'liquidjs'
+import { isLayoutTag, isIfTag, isUnlessTag, isLiquidTag, isCaseTag, isCaptureTag, isTablerowTag, isForTag } from './type-guards'
+
+/**
+ * iterate over all `{{ output }}`
+ */
+export function * getOutputs (templates: Template[]): Generator<Output, void> {
+  for (const template of templates) {
+    if (template instanceof Tag) {
+      if (isIfTag(template) || isUnlessTag(template) || isCaseTag(template)) {
+        for (const branch of template.branches) {
+          yield * getOutputs(branch.templates)
+        }
+        yield * getOutputs(template.elseTemplates)
+      } else if (isForTag(template)) {
+        yield * getOutputs(template.templates)
+        yield * getOutputs(template.elseTemplates)
+      } else if (isLiquidTag(template) || isCaptureTag(template) || isTablerowTag(template) || isLayoutTag(template)) {
+        yield * getOutputs(template.templates)
+      }
+    } else if (template instanceof Output) {
+      yield template
+    }
+  }
+}
diff --git a/demo/template/index.ts b/demo/template/index.ts
new file mode 100644
index 000000000..2beb2d6c8
--- /dev/null
+++ b/demo/template/index.ts
@@ -0,0 +1,16 @@
+import { Liquid } from 'liquidjs'
+import { getOutputs } from './get-outputs'
+
+const engine = new Liquid({
+  root: __dirname,
+  extname: '.liquid'
+})
+
+const templates = engine.parseFileSync('todolist')
+
+for (const output of getOutputs(templates)) {
+  const token = output.token
+  const [line, col] = token.getPosition()
+  const text = token.getText()
+  console.log(`[${line}:${col}] ${text}`)
+}
diff --git a/demo/template/package.json b/demo/template/package.json
new file mode 100644
index 000000000..9eb728ad2
--- /dev/null
+++ b/demo/template/package.json
@@ -0,0 +1,17 @@
+{
+  "name": "liquidjs-demo-template",
+  "private": true,
+  "description": "liquid template parsing",
+  "main": "index.ts",
+  "scripts": {
+    "start": "ts-node index.ts"
+  },
+  "dependencies": {
+    "liquidjs": "latest",
+    "ts-node": "^8.10.2",
+    "typescript": "^4.2.4"
+  },
+  "devDependencies": {
+    "@types/node": "^14.14.37"
+  }
+}
diff --git a/demo/template/todolist.liquid b/demo/template/todolist.liquid
new file mode 100644
index 000000000..8564cc3a2
--- /dev/null
+++ b/demo/template/todolist.liquid
@@ -0,0 +1,13 @@
+{% layout 'html.liquid' %}
+
+<h1>{{ title | capitalize }}</h1>
+<a>
+  {% if authed %} Sign out {{ username }}
+  {% else %} Sign in
+  {% endif %}
+</a>
+<ul>
+  {% for todo in todos %}
+    <p>{{ todo }}</p>
+  {% endfor %}
+</ul>
\ No newline at end of file
diff --git a/demo/template/tsconfig.json b/demo/template/tsconfig.json
new file mode 100644
index 000000000..7a6be845e
--- /dev/null
+++ b/demo/template/tsconfig.json
@@ -0,0 +1,8 @@
+{
+  "compilerOptions": {
+    "downlevelIteration": true,
+    "types": [
+      "node"
+    ]
+  }
+}
\ No newline at end of file
diff --git a/demo/template/type-guards.ts b/demo/template/type-guards.ts
new file mode 100644
index 000000000..47f12fe26
--- /dev/null
+++ b/demo/template/type-guards.ts
@@ -0,0 +1,33 @@
+import { LayoutTag, ForTag, LiquidTag, CaptureTag, CaseTag, UnlessTag, TablerowTag, Tag, IfTag } from 'liquidjs'
+
+export function isIfTag (tag: Tag): tag is IfTag {
+  return tag.name === 'if'
+}
+
+export function isUnlessTag (tag: Tag): tag is UnlessTag {
+  return tag.name === 'unless'
+}
+
+export function isLiquidTag (tag: Tag): tag is LiquidTag {
+  return tag.name === 'liquid'
+}
+
+export function isCaseTag (tag: Tag): tag is CaseTag {
+  return tag.name === 'case'
+}
+
+export function isCaptureTag (tag: Tag): tag is CaptureTag {
+  return tag.name === 'capture'
+}
+
+export function isTablerowTag (tag: Tag): tag is TablerowTag {
+  return tag.name === 'tablerow'
+}
+
+export function isForTag (tag: Tag): tag is ForTag {
+  return tag.name === 'for'
+}
+
+export function isLayoutTag (tag: Tag): tag is LayoutTag {
+  return tag.name === 'layout'
+}
diff --git a/src/index.ts b/src/index.ts
index a73cb973e..56e39d7fd 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -6,10 +6,10 @@ export { Drop } from './drop'
 export { Emitter } from './emitters'
 export { defaultOperators, Operators, evalToken, evalQuotedToken, Expression, isFalsy, isTruthy } from './render'
 export { Context, Scope } from './context'
-export { Value, Hash, Template, FilterImplOptions, Tag, Filter } from './template'
+export { Value, Hash, Template, FilterImplOptions, Tag, Filter, Output } from './template'
 export { Token, TopLevelToken, TagToken, ValueToken } from './tokens'
 export { TokenKind, Tokenizer, ParseStream } from './parser'
 export { filters } from './filters'
-export { tags } from './tags'
+export * from './tags'
 export { defaultOptions } from './liquid-options'
 export { Liquid } from './liquid'
diff --git a/src/tags/block.ts b/src/tags/block.ts
index b59c600bd..450d6c136 100644
--- a/src/tags/block.ts
+++ b/src/tags/block.ts
@@ -4,8 +4,8 @@ import { BlockDrop } from '../drop'
 import { Liquid, TagToken, TopLevelToken, Template, Context, Emitter, Tag } from '..'
 
 export default class extends Tag {
-  private block: string
-  private tpls: Template[] = []
+  block: string
+  templates: Template[] = []
   constructor (token: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
     super(token, remainTokens, liquid)
     const match = /\w+/.exec(token.args)
@@ -14,7 +14,7 @@ export default class extends Tag {
       const token = remainTokens.shift()!
       if (isTagToken(token) && token.name === 'endblock') return
       const template = liquid.parser.parseToken(token, remainTokens)
-      this.tpls.push(template)
+      this.templates.push(template)
     }
     throw new Error(`tag ${token.getText()} not closed`)
   }
@@ -29,12 +29,12 @@ export default class extends Tag {
   }
 
   private getBlockRender (ctx: Context) {
-    const { liquid, tpls } = this
+    const { liquid, templates } = this
     const renderChild = ctx.getRegister('blocks')[this.block]
     const renderCurrent = function * (superBlock: BlockDrop, emitter: Emitter) {
       // add {{ block.super }} support when rendering
       ctx.push({ block: superBlock })
-      yield liquid.renderer.renderTemplates(tpls, ctx, emitter)
+      yield liquid.renderer.renderTemplates(templates, ctx, emitter)
       ctx.pop()
     }
     return renderChild
diff --git a/src/tags/capture.ts b/src/tags/capture.ts
index 95a7c40c5..5abf02720 100644
--- a/src/tags/capture.ts
+++ b/src/tags/capture.ts
@@ -3,8 +3,8 @@ import { evalQuotedToken } from '../render'
 import { isTagToken } from '../util'
 
 export default class extends Tag {
-  private variable: string
-  private templates: Template[] = []
+  variable: string
+  templates: Template[] = []
   constructor (tagToken: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
     super(tagToken, remainTokens, liquid)
     const tokenizer = new Tokenizer(tagToken.args, this.liquid.options.operators)
diff --git a/src/tags/case.ts b/src/tags/case.ts
index 8cad4bbd2..a7608f6b5 100644
--- a/src/tags/case.ts
+++ b/src/tags/case.ts
@@ -1,12 +1,12 @@
 import { ValueToken, Liquid, Tokenizer, toValue, evalToken, Value, Emitter, TagToken, TopLevelToken, Context, Template, Tag, ParseStream } from '..'
 
 export default class extends Tag {
-  private cond: Value
-  private cases: { val?: ValueToken, templates: Template[] }[] = []
-  private elseTemplates: Template[] = []
+  value: Value
+  branches: { value?: ValueToken, templates: Template[] }[] = []
+  elseTemplates: Template[] = []
   constructor (tagToken: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
     super(tagToken, remainTokens, liquid)
-    this.cond = new Value(tagToken.args, this.liquid)
+    this.value = new Value(tagToken.args, this.liquid)
     this.elseTemplates = []
 
     let p: Template[] = []
@@ -18,8 +18,8 @@ export default class extends Tag {
 
         while (!tokenizer.end()) {
           const value = tokenizer.readValue()
-          this.cases.push({
-            val: value,
+          this.branches.push({
+            value: value,
             templates: p
           })
           tokenizer.readTo(',')
@@ -37,10 +37,10 @@ export default class extends Tag {
 
   * render (ctx: Context, emitter: Emitter): Generator<unknown, unknown, unknown> {
     const r = this.liquid.renderer
-    const cond = toValue(yield this.cond.value(ctx, ctx.opts.lenientIf))
-    for (const branch of this.cases) {
-      const val = yield evalToken(branch.val, ctx, ctx.opts.lenientIf)
-      if (val === cond) {
+    const value = toValue(yield this.value.value(ctx, ctx.opts.lenientIf))
+    for (const branch of this.branches) {
+      const target = yield evalToken(branch.value, ctx, ctx.opts.lenientIf)
+      if (target === value) {
         yield r.renderTemplates(branch.templates, ctx, emitter)
         return
       }
diff --git a/src/tags/for.ts b/src/tags/for.ts
index 110d04ee2..1ed0f5509 100644
--- a/src/tags/for.ts
+++ b/src/tags/for.ts
@@ -7,11 +7,11 @@ const MODIFIERS = ['offset', 'limit', 'reversed']
 type valueof<T> = T[keyof T]
 
 export default class extends Tag {
-  private variable: string
-  private collection: ValueToken
-  private hash: Hash
-  private templates: Template[]
-  private elseTemplates: Template[]
+  variable: string
+  collection: ValueToken
+  hash: Hash
+  templates: Template[]
+  elseTemplates: Template[]
 
   constructor (token: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
     super(token, remainTokens, liquid)
diff --git a/src/tags/if.ts b/src/tags/if.ts
index c619c9142..8e6651793 100644
--- a/src/tags/if.ts
+++ b/src/tags/if.ts
@@ -1,19 +1,19 @@
 import { Liquid, Tag, Value, Emitter, isTruthy, TagToken, TopLevelToken, Context, Template } from '..'
 
 export default class extends Tag {
-  private branches: { predicate: Value, templates: Template[] }[] = []
-  private elseTemplates: Template[] = []
+  branches: { value: Value, templates: Template[] }[] = []
+  elseTemplates: Template[] = []
 
   constructor (tagToken: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
     super(tagToken, remainTokens, liquid)
     let p
     liquid.parser.parseStream(remainTokens)
       .on('start', () => this.branches.push({
-        predicate: new Value(tagToken.args, this.liquid),
+        value: new Value(tagToken.args, this.liquid),
         templates: (p = [])
       }))
       .on('tag:elsif', (token: TagToken) => this.branches.push({
-        predicate: new Value(token.args, this.liquid),
+        value: new Value(token.args, this.liquid),
         templates: (p = [])
       }))
       .on('tag:else', () => (p = this.elseTemplates))
@@ -26,9 +26,9 @@ export default class extends Tag {
   * render (ctx: Context, emitter: Emitter): Generator<unknown, void, string> {
     const r = this.liquid.renderer
 
-    for (const { predicate, templates } of this.branches) {
-      const value = yield predicate.value(ctx, ctx.opts.lenientIf)
-      if (isTruthy(value, ctx)) {
+    for (const { value, templates } of this.branches) {
+      const v = yield value.value(ctx, ctx.opts.lenientIf)
+      if (isTruthy(v, ctx)) {
         yield r.renderTemplates(templates, ctx, emitter)
         return
       }
diff --git a/src/tags/index.ts b/src/tags/index.ts
index b9763a67c..9edf91f51 100644
--- a/src/tags/index.ts
+++ b/src/tags/index.ts
@@ -1,26 +1,48 @@
-import assign from './assign'
-import For from './for'
-import capture from './capture'
-import Case from './case'
-import comment from './comment'
-import include from './include'
-import render from './render'
-import decrement from './decrement'
-import cycle from './cycle'
-import If from './if'
-import increment from './increment'
-import layout from './layout'
-import block from './block'
-import raw from './raw'
-import tablerow from './tablerow'
-import unless from './unless'
-import Break from './break'
-import Continue from './continue'
-import echo from './echo'
-import liquid from './liquid'
-import inlineComment from './inline-comment'
+import AssignTag from './assign'
+import ForTag from './for'
+import CaptureTag from './capture'
+import CaseTag from './case'
+import CommentTag from './comment'
+import IncludeTag from './include'
+import RenderTag from './render'
+import DecrementTag from './decrement'
+import CycleTag from './cycle'
+import IfTag from './if'
+import IncrementTag from './increment'
+import LayoutTag from './layout'
+import BlockTag from './block'
+import RawTag from './raw'
+import TablerowTag from './tablerow'
+import UnlessTag from './unless'
+import BreakTag from './break'
+import ContinueTag from './continue'
+import EchoTag from './echo'
+import LiquidTag from './liquid'
+import InlineCommentTag from './inline-comment'
 import type { TagClass } from '../template/tag'
 
 export const tags: Record<string, TagClass> = {
-  assign, 'for': For, capture, 'case': Case, comment, include, render, decrement, increment, cycle, 'if': If, layout, block, raw, tablerow, unless, 'break': Break, 'continue': Continue, echo, liquid, '#': inlineComment
+  assign: AssignTag,
+  'for': ForTag,
+  capture: CaptureTag,
+  'case': CaseTag,
+  comment: CommentTag,
+  include: IncludeTag,
+  render: RenderTag,
+  decrement: DecrementTag,
+  increment: IncrementTag,
+  cycle: CycleTag,
+  'if': IfTag,
+  layout: LayoutTag,
+  block: BlockTag,
+  raw: RawTag,
+  tablerow: TablerowTag,
+  unless: UnlessTag,
+  'break': BreakTag,
+  'continue': ContinueTag,
+  echo: EchoTag,
+  liquid: LiquidTag,
+  '#': InlineCommentTag
 }
+
+export { AssignTag, ForTag, CaptureTag, CaseTag, CommentTag, IncludeTag, RenderTag, DecrementTag, IncrementTag, CycleTag, IfTag, LayoutTag, BlockTag, RawTag, TablerowTag, UnlessTag, BreakTag, ContinueTag, EchoTag, LiquidTag, InlineCommentTag }
diff --git a/src/tags/layout.ts b/src/tags/layout.ts
index b1700feb0..7ffc04da1 100644
--- a/src/tags/layout.ts
+++ b/src/tags/layout.ts
@@ -4,23 +4,23 @@ import { parseFilePath, renderFilePath, ParsedFileName } from './render'
 import { BlankDrop } from '../drop'
 
 export default class extends Tag {
-  private hash: Hash
-  private tpls: Template[]
-  private file?: ParsedFileName
+  args: Hash
+  templates: Template[]
+  file?: ParsedFileName
   constructor (token: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
     super(token, remainTokens, liquid)
     const tokenizer = new Tokenizer(token.args, this.liquid.options.operators)
     this.file = parseFilePath(tokenizer, this.liquid)
     this['currentFile'] = token.file
-    this.hash = new Hash(tokenizer.remaining())
-    this.tpls = this.liquid.parser.parseTokens(remainTokens)
+    this.args = new Hash(tokenizer.remaining())
+    this.templates = this.liquid.parser.parseTokens(remainTokens)
   }
   * render (ctx: Context, emitter: Emitter): Generator<unknown, unknown, unknown> {
-    const { liquid, hash, file } = this
+    const { liquid, args, file } = this
     const { renderer } = liquid
     if (file === undefined) {
       ctx.setRegister('blockMode', BlockMode.OUTPUT)
-      yield renderer.renderTemplates(this.tpls, ctx, emitter)
+      yield renderer.renderTemplates(this.templates, ctx, emitter)
       return
     }
     const filepath = (yield renderFilePath(this.file, ctx, liquid)) as string
@@ -29,7 +29,7 @@ export default class extends Tag {
 
     // render remaining contents and store rendered results
     ctx.setRegister('blockMode', BlockMode.STORE)
-    const html = yield renderer.renderTemplates(this.tpls, ctx)
+    const html = yield renderer.renderTemplates(this.templates, ctx)
     const blocks = ctx.getRegister('blocks')
 
     // set whole content to anonymous block if anonymous doesn't specified
@@ -37,7 +37,7 @@ export default class extends Tag {
     ctx.setRegister('blockMode', BlockMode.OUTPUT)
 
     // render the layout file use stored blocks
-    ctx.push((yield hash.render(ctx)) as Scope)
+    ctx.push((yield args.render(ctx)) as Scope)
     yield renderer.renderTemplates(templates, ctx, emitter)
     ctx.pop()
   }
diff --git a/src/tags/liquid.ts b/src/tags/liquid.ts
index d733529b8..18a4ff7df 100644
--- a/src/tags/liquid.ts
+++ b/src/tags/liquid.ts
@@ -1,14 +1,14 @@
 import { Template, Tokenizer, Emitter, Liquid, TopLevelToken, TagToken, Context, Tag } from '..'
 
 export default class extends Tag {
-  private tpls: Template[]
+  templates: Template[]
   constructor (token: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
     super(token, remainTokens, liquid)
     const tokenizer = new Tokenizer(token.args, this.liquid.options.operators)
     const tokens = tokenizer.readLiquidTagTokens(this.liquid.options)
-    this.tpls = this.liquid.parser.parseTokens(tokens)
+    this.templates = this.liquid.parser.parseTokens(tokens)
   }
   * render (ctx: Context, emitter: Emitter): Generator<unknown, void, unknown> {
-    yield this.liquid.renderer.renderTemplates(this.tpls, ctx, emitter)
+    yield this.liquid.renderer.renderTemplates(this.templates, ctx, emitter)
   }
 }
diff --git a/src/tags/tablerow.ts b/src/tags/tablerow.ts
index 23ed63ad0..c69fe8d9f 100644
--- a/src/tags/tablerow.ts
+++ b/src/tags/tablerow.ts
@@ -4,10 +4,10 @@ import { TablerowloopDrop } from '../drop/tablerowloop-drop'
 import { Tokenizer } from '../parser/tokenizer'
 
 export default class extends Tag {
-  private variable: string
-  private hash: Hash
-  private templates: Template[]
-  private collection: ValueToken
+  variable: string
+  args: Hash
+  templates: Template[]
+  collection: ValueToken
   constructor (tagToken: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
     super(tagToken, remainTokens, liquid)
     const tokenizer = new Tokenizer(tagToken.args, this.liquid.options.operators)
@@ -23,7 +23,7 @@ export default class extends Tag {
 
     this.variable = variable.content
     this.collection = collectionToken
-    this.hash = new Hash(tokenizer.remaining())
+    this.args = new Hash(tokenizer.remaining())
     this.templates = []
 
     let p
@@ -40,12 +40,12 @@ export default class extends Tag {
 
   * render (ctx: Context, emitter: Emitter): Generator<unknown, void, unknown> {
     let collection = toEnumerable(yield evalToken(this.collection, ctx))
-    const hash = (yield this.hash.render(ctx)) as Record<string, any>
-    const offset = hash.offset || 0
-    const limit = (hash.limit === undefined) ? collection.length : hash.limit
+    const args = (yield this.args.render(ctx)) as Record<string, any>
+    const offset = args.offset || 0
+    const limit = (args.limit === undefined) ? collection.length : args.limit
 
     collection = collection.slice(offset, offset + limit)
-    const cols = hash.cols || collection.length
+    const cols = args.cols || collection.length
 
     const r = this.liquid.renderer
     const tablerowloop = new TablerowloopDrop(collection.length, cols, this.collection.getText(), this.variable)
diff --git a/src/tags/unless.ts b/src/tags/unless.ts
index 15f03cc06..390d7931b 100644
--- a/src/tags/unless.ts
+++ b/src/tags/unless.ts
@@ -1,19 +1,19 @@
 import { Liquid, Tag, Value, TopLevelToken, Template, Emitter, isTruthy, isFalsy, Context, TagToken } from '..'
 
 export default class extends Tag {
-  private branches: { predicate: Value, test: (val: any, ctx: Context) => boolean, templates: Template[] }[] = []
-  private elseTemplates: Template[] = []
+  branches: { value: Value, test: (val: any, ctx: Context) => boolean, templates: Template[] }[] = []
+  elseTemplates: Template[] = []
   constructor (tagToken: TagToken, remainTokens: TopLevelToken[], liquid: Liquid) {
     super(tagToken, remainTokens, liquid)
     let p
     this.liquid.parser.parseStream(remainTokens)
       .on('start', () => this.branches.push({
-        predicate: new Value(tagToken.args, this.liquid),
+        value: new Value(tagToken.args, this.liquid),
         test: isFalsy,
         templates: (p = [])
       }))
       .on('tag:elsif', (token: TagToken) => this.branches.push({
-        predicate: new Value(token.args, this.liquid),
+        value: new Value(token.args, this.liquid),
         test: isTruthy,
         templates: (p = [])
       }))
@@ -27,9 +27,9 @@ export default class extends Tag {
   * render (ctx: Context, emitter: Emitter): Generator<unknown, unknown, unknown> {
     const r = this.liquid.renderer
 
-    for (const { predicate, test, templates } of this.branches) {
-      const value = yield predicate.value(ctx, ctx.opts.lenientIf)
-      if (test(value, ctx)) {
+    for (const { value, test, templates } of this.branches) {
+      const v = yield value.value(ctx, ctx.opts.lenientIf)
+      if (test(v, ctx)) {
         yield r.renderTemplates(templates, ctx, emitter)
         return
       }
diff --git a/src/template/output.ts b/src/template/output.ts
index 9c20bfff8..f97313eb9 100644
--- a/src/template/output.ts
+++ b/src/template/output.ts
@@ -7,7 +7,7 @@ import { Liquid } from '../liquid'
 import { Filter } from './filter'
 
 export class Output extends TemplateImpl<OutputToken> implements Template {
-  private value: Value
+  value: Value
   public constructor (token: OutputToken, liquid: Liquid) {
     super(token)
     this.value = new Value(token.content, liquid)