feat: introduce trim config option

src/constants.js

@@ -4,5 +4,6 @@
 export const CONFIG = {
   ignore: {},
   strict: false,
-  tab_size: 2
+  tab_size: 2,
+  trim: {}
 }

src/prettify.js

@@ -1,13 +1,18 @@
 import { closify } from './closify.js'
 import { minify } from './minify.js'
-import { ignoreElement, isHtml, validateConfig } from './utils.js'
+import { ignoreElement, isHtml, trimify, validateConfig } from './utils.js'
 import { CONFIG } from './constants.js'
 
 /**
  * @type {boolean}
  */
 let strict
 
+/**
+ * @type {Record<string, string>}
+ */
+let trim
+
 /**
  * @type {{ line: string[] }}
  */
@@ -47,6 +52,10 @@ const enqueue = (html) => {
  */
 const preprocess = (html) => {
   html = closify(html, false)
+
+  if (trim)
+    trimify(html, trim)
+
   html = minify(html, false)
   html = enqueue(html)
 
@@ -148,6 +157,7 @@ export const prettify = (html, config) => {
   strict = validated_config.strict
 
   const ignore = Object.keys(validated_config.ignore).length > 0
+  trim = validated_config.trim
 
   /* Protect ignored elements. */
   if (ignore) {

src/types/internal.d.ts

@@ -2,6 +2,7 @@ export interface DefaultConfig {
 	ignore: Record<string, string>;
 	strict: boolean;
 	tab_size: number;
+	trim: Record<string, string>;
 }
 
 type RecursiveRequired<T> = {

src/utils.js

@@ -88,6 +88,27 @@ const protectElement = (match, capture) => {
   })
 }
 
+/**
+ * Trim leading and trailing whitespace characters.
+ * 
+ * @param {string} html
+ * @param {Record<string, string>} trim
+ * @returns {string}
+ */
+export const trimify = (html, trim) => {
+  for (let e = 0; e < Object.keys(trim).length; e++) {
+    /* Whitespace character must be escaped with '\' or RegExp() won't include it. */
+    const leading_whitespace = new RegExp(`(<${trim[e]}[^>]*>)\\s+`, "g")
+    const trailing_whitespace = new RegExp(`\\s+(</${trim[e]}>)`, "g")
+
+    html = html
+      .replace(leading_whitespace, '$1')
+      .replace(trailing_whitespace, '$1')
+  }
+
+  return html
+}
+
 /**
  * Unprotect an element by removing entities.
  * 
@@ -115,7 +136,11 @@ const unprotectElement = (match, capture) => {
 export const validateConfig = (config) => {
   if (typeof config !== 'object') throw new Error('Config must be an object.')
 
-  const config_empty = !(Object.hasOwn(config, 'tab_size') || Object.hasOwn(config, 'strict') || Object.hasOwn(config, 'ignore'))
+  const config_empty = !(
+    Object.hasOwn(config, 'tab_size') || 
+    Object.hasOwn(config, 'strict') || 
+    Object.hasOwn(config, 'ignore') || 
+    Object.hasOwn(config, 'trim'))
   if (config_empty) return CONFIG
 
   let tab_size = config.tab_size
@@ -139,6 +164,8 @@ export const validateConfig = (config) => {
     throw new Error('Strict config must be a boolean.')
   if (Object.hasOwn(config, 'ignore') && (!Array.isArray(config.ignore) || !config.ignore?.every((e) => typeof e === 'string')))
     throw new Error('Ignore config must be an array of strings.')
+  if (Object.hasOwn(config, 'trim') && (!Array.isArray(config.trim) || !config.trim?.every((e) => typeof e === 'string')))
+    throw new Error('Trim config must be an array of strings.')
 
   return mergeConfig(CONFIG, config)
 

tests/all.spec.js

@@ -2,6 +2,7 @@ import { closify } from '../src/closify.js'
 import { entify } from '../src/entify.js'
 import { minify } from '../src/minify.js'
 import { prettify } from '../src/prettify.js'
+import { trimify } from '../src/utils.js'
 import { expect, test } from 'vitest'
 
 const ugly_html = `<form id="3"     >     <!-- 
@@ -78,11 +79,25 @@ Please()
 </code></pre>
 `
 
+const trim_leading_whitespace = `<div> 
+
+  Hello</div>`
+const trim_trailing_whitespace = `<div>Hello
+
+  
+
+</div>`
+
 // @ts-ignore
 const testConfig = async (config) => {
   return await prettify(config_html, config)
 }
 
+test('Trimify', () => {
+  expect(trimify(trim_leading_whitespace, { '0': 'div' })).toBe('<div>Hello</div>')
+  expect(trimify(trim_trailing_whitespace, { '0': 'div' })).toBe('<div>Hello</div>')
+})
+
 test('Prettify', () => {
   expect(prettify(ugly_html)).toBe(pretty_html)
 })
@@ -194,3 +209,7 @@ test('Tab size config', () => {
 test('Catches invalid ignore config', async () => {
   await expect(testConfig({ ignore: [ 'script', 1 ]})).rejects.toThrow('Ignore config must be an array of strings.')
 })
+
+test('Catches invalid trim config', async () => {
+  await expect(testConfig({ trim: [ 'textarea', 1 ]})).rejects.toThrow('Trim config must be an array of strings.')
+})

types/index.d.ts

@@ -3,12 +3,14 @@ declare module 'htmlfy' {
     ignore?: string[];
     strict?: boolean;
     tab_size?: number;
+    trim?: string[];
   }
 
   export interface Config {
     ignore: Record<string, string>;
     strict: boolean;
     tab_size: number;
+    trim: Record<string, string>;
   }
 
   /**