refactor: use string-remove-widows library for preventing widow words

package.json

@@ -69,8 +69,8 @@
     "posthtml-safe-class-names": "^1.0.8",
     "posthtml-url-parameters": "^1.0.4",
     "pretty": "^2.0.0",
-    "prevent-widows": "^1.0.2",
     "query-string": "^7.1.0",
+    "string-remove-widows": "^2.1.0",
     "string-strip-html": "^8.2.0",
     "tailwindcss": "^3.1.0"
   },

src/transformers/index.js

@@ -49,7 +49,7 @@ exports.prettify = (html, config) => prettify(html, config, true)
 exports.ensureSixHEX = (html, config) => ensureSixHEX(html, config)
 exports.withFilters = (html, config) => filters(html, config, true)
 exports.addURLParams = (html, config) => addURLParams(html, config, true)
-exports.preventWidows = (html, config) => preventWidows(html, config, true)
+exports.preventWidows = (html, config) => preventWidows(html, config)
 exports.replaceStrings = (html, config) => replaceStrings(html, config, true)
 exports.safeClassNames = (html, config) => safeClassNames(html, config, true)
 exports.removeUnusedCSS = (html, config) => removeUnusedCSS(html, config, true)

src/transformers/preventWidows.js

@@ -1,13 +1,80 @@
-const {get} = require('lodash')
 const posthtml = require('posthtml')
-const preventWidows = require('prevent-widows')
+const {get, isEmpty} = require('lodash')
+const {removeWidows} = require('string-remove-widows')
 
-module.exports = async (html, config = {}, direct = false) => {
-  const posthtmlOptions = get(config, 'build.posthtml.options', {})
+module.exports = async (html, config = {}) => {
+  if (isEmpty(config)) {
+    return removeWidows(html).res
+  }
+
+  const posthtmlOptions = get(config, 'build.posthtml.options', {recognizeNoValueAttribute: true})
+
+  return posthtml([removeWidowsPlugin(config)]).process(html, posthtmlOptions).then(result => result.html)
+}
+
+const removeWidowsPlugin = options => tree => {
+  const {attrName = 'prevent-widows', ...removeWidowsOptions} = get(options, 'widowWords', options)
+
+  removeWidowsOptions.minWordCount = removeWidowsOptions.minWordCount || 3
+
+  // Ignore defaults
+  const mappings = [
+    // Jinja-like
+    {
+      heads: '{{',
+      tails: '}}'
+    },
+    {
+      heads: ['{% if', '{%- if'],
+      tails: ['{% endif', '{%- endif']
+    },
+    {
+      heads: ['{% for', '{%- for'],
+      tails: ['{% endfor', '{%- endfor']
+    },
+    {
+      heads: ['{%', '{%-'],
+      tails: ['%}', '-%}']
+    },
+    {
+      heads: '{#',
+      tails: '#}'
+    },
+    // ASP/Hexo-like
+    {
+      heads: ['<%', '<%=', '<%-'],
+      tails: ['%>', '=%>', '-%>']
+    },
+    // MSO comments
+    {
+      heads: '<!--[',
+      tails: ']>'
+    },
+    // <![endif]-->
+    {
+      heads: '<![',
+      tails: ']--><'
+    }
+  ]
+
+  if (Array.isArray(removeWidowsOptions.ignore)) {
+    removeWidowsOptions.ignore.forEach(pair => mappings.push(pair))
+  }
+
+  if (typeof removeWidowsOptions.ignore !== 'string') {
+    removeWidowsOptions.ignore = mappings
+  }
+
+  const process = node => {
+    if (node.attrs && Object.keys(node.attrs).includes(attrName)) {
+      const widowsRemovedString = removeWidows(tree.render(node.content), removeWidowsOptions).res
+
+      node.content = tree.render(tree.parser(widowsRemovedString))
+      node.attrs[attrName] = false
+    }
 
-  if (direct) {
-    return preventWidows(html)
+    return node
   }
 
-  return posthtml([preventWidows.posthtml()]).process(html, posthtmlOptions).then(result => result.html)
+  return tree.walk(process)
 }

test/test-transformers.js

@@ -373,9 +373,62 @@ test('attribute to style', async t => {
 })
 
 test('prevent widows', async t => {
-  const html = await Maizzle.preventWidows('lorem ipsum dolor')
+  const html = await Maizzle.preventWidows(`
+    <!--[if mso]>
+      <p>A paragraph inside an Outlook MSO comment</p>
+    <![endif]-->
+    <div>Text following an MSO comment</div>
+  `)
+
+  t.is(html, `
+    <!--[if mso]>
+      <p>A paragraph inside an Outlook MSO&nbsp;comment</p>
+    <![endif]-->
+    <div>Text following an MSO&nbsp;comment</div>
+  `)
+})
+
+test('prevent widows (with options)', async t => {
+  const html = await Maizzle.preventWidows(`
+    <div no-widows>
+      <p>Text following an MSO comment</p>
+      <!--[if mso 15]>
+        <p>A paragraph inside an Outlook MSO comment</p>
+        <p>unescaped {{{ foo }}}</p>
+      <![endif]-->
+      <p>expression {{ foo }}</p>
+      <!--[if !mso]><!-->
+        <div>All Outlooks will ignore this</div>
+      <!--<![endif]-->
+      <p>unescaped {{{ foo }}}</p>
+    </div>
+    <p>Should not remove widows here</p>
+  `, {
+    attrName: 'no-widows',
+    minWordCount: 3,
+    ignore: [
+      {
+        heads: 'foo',
+        tails: 'bar'
+      }
+    ]
+  })
 
-  t.is(html, 'lorem ipsum&nbsp;dolor')
+  t.is(html, `
+    <div>
+      <p>Text following an MSO&nbsp;comment</p>
+      <!--[if mso 15]>
+        <p>A paragraph inside an Outlook MSO&nbsp;comment</p>
+        <p>unescaped {{{ foo }}}</p>
+      <![endif]-->
+      <p>expression {{ foo }}</p>
+      <!--[if !mso]><!-->
+        <div>All Outlooks will ignore this</div>
+      <!--<![endif]-->
+      <p>unescaped {{{ foo }}}</p>
+    </div>
+    <p>Should not remove widows here</p>
+  `)
 })
 
 test('markdown (disabled)', async t => {