Feature/add custom element built in support (#137)

fixes #136 

* adds template literal support for extended built-in elements (custom elements V1 spec)
* browserify and babel transform upgrades

lib/babel.js

@@ -51,6 +51,12 @@ module.exports = (babel) => {
   const t = babel.types
   const nanohtmlModuleNames = ['nanohtml', 'bel', 'yo-yo', 'choo/html']
 
+  /**
+   * Returns an object which specifies the custom elements by which a built-in is extended.
+   */
+  const createExtendsObjectExpression = (is) =>
+    t.objectExpression([t.objectProperty(t.identifier('is'), t.stringLiteral(is))])
+
   /**
    * Returns a node that creates a namespaced HTML element.
    */
@@ -60,6 +66,15 @@ module.exports = (babel) => {
       [ns, t.stringLiteral(tag)]
     )
 
+  /**
+   * Returns a node that creates a extended namespaced HTML element.
+   */
+  const createNsCustomBuiltIn = (ns, tag, is) =>
+    t.callExpression(
+      t.memberExpression(t.identifier('document'), t.identifier('createElementNS')),
+      [ns, t.stringLiteral(tag), createExtendsObjectExpression(is)]
+    )
+
   /**
    * Returns a node that creates an element.
   */
@@ -69,6 +84,15 @@ module.exports = (babel) => {
       [t.stringLiteral(tag)]
     )
 
+  /**
+   * Returns a node that creates an extended element.
+   */
+  const createCustomBuiltIn = (tag, is) =>
+    t.callExpression(
+      t.memberExpression(t.identifier('document'), t.identifier('createElement')),
+      [t.stringLiteral(tag), createExtendsObjectExpression(is)]
+    )
+
   /**
    * Returns a node that creates a comment.
    */
@@ -195,10 +219,20 @@ module.exports = (babel) => {
 
       const result = []
 
+      var isCustomElement = props.is
+      delete props.is
+
       // Use the SVG namespace for svg elements.
       if (SVG_TAGS.includes(tag)) {
         state.svgNamespaceId.used = true
-        result.push(t.assignmentExpression('=', id, createNsElement(state.svgNamespaceId, tag)))
+
+        if (isCustomElement) {
+          result.push(t.assignmentExpression('=', id, createNsCustomBuiltIn(state.svgNamespaceId, tag, isCustomElement)))
+        } else {
+          result.push(t.assignmentExpression('=', id, createNsElement(state.svgNamespaceId, tag)))
+        }
+      } else if (isCustomElement) {
+        result.push(t.assignmentExpression('=', id, createCustomBuiltIn(tag, isCustomElement)))
       } else {
         result.push(t.assignmentExpression('=', id, createElement(tag)))
       }

lib/browser.js

@@ -25,11 +25,24 @@ function nanoHtmlCreateElement (tag, props, children) {
     delete props.namespace
   }
 
+  // If we are extending a builtin element
+  var isCustomElement = false
+  if (props.is) {
+    isCustomElement = props.is
+    delete props.is
+  }
+
   // Create the element
   if (ns) {
-    el = document.createElementNS(ns, tag)
+    if (isCustomElement) {
+      el = document.createElementNS(ns, tag, { is: isCustomElement })
+    } else {
+      el = document.createElementNS(ns, tag)
+    }
   } else if (tag === COMMENT_TAG) {
     return document.createComment(props.comment)
+  } else if (isCustomElement) {
+    el = document.createElement(tag, { is: isCustomElement })
   } else {
     el = document.createElement(tag)
   }

lib/browserify-transform.js

@@ -136,9 +136,19 @@ function processNode (node, args) {
       namespace = SVGNS
     }
 
+    // Whether this element is extended
+    var isCustomElement = props.is
+    delete props.is
+
     // Create the element
     if (namespace) {
-      res.push('var ' + elname + ' = document.createElementNS(' + JSON.stringify(namespace) + ', ' + JSON.stringify(tag) + ')')
+      if (isCustomElement) {
+        res.push('var ' + elname + ' = document.createElementNS(' + JSON.stringify(namespace) + ', ' + JSON.stringify(tag) + ', { is: ' + JSON.stringify(isCustomElement) + ' })')
+      } else {
+        res.push('var ' + elname + ' = document.createElementNS(' + JSON.stringify(namespace) + ', ' + JSON.stringify(tag) + ')')
+      }
+    } else if (isCustomElement) {
+      res.push('var ' + elname + ' = document.createElement(' + JSON.stringify(tag) + ', { is: ' + JSON.stringify(isCustomElement) + ' })')
     } else {
       res.push('var ' + elname + ' = document.createElement(' + JSON.stringify(tag) + ')')
     }

tests/babel/fixtures/custom-build-in.expected.js

@@ -0,0 +1,6 @@
+var _div,
+    _appendChild = require('nanohtml/lib/append-child');
+
+_div = document.createElement('div', {
+  is: 'my-div'
+}), _appendChild(_div, ['\n    Hello world\n  ']), _div;

tests/babel/fixtures/custom-build-in.js

@@ -0,0 +1,7 @@
+import html from 'nanohtml'
+
+html`
+  <div is="my-div">
+    Hello world
+  </div>
+`

tests/babel/index.js

@@ -37,6 +37,7 @@ function testFixture (name, opts) {
 }
 
 testFixture('simple')
+testFixture('custom-build-in')
 testFixture('empty')
 testFixture('this')
 testFixture('variableNames')

tests/browser/elements.js

@@ -185,3 +185,27 @@ test('allow objects to be passed', function (t) {
   t.ok(result.outerHTML.indexOf('<div foo="bar">hey</div>') !== -1, 'contains foo="bar"')
   t.end()
 })
+
+test('supports extended build-in elements', function (t) {
+  t.plan(1)
+
+  var originalCreateElement = document.createElement
+  var optionsArg
+
+  // this iife is a must to avoid illegal invocation type errors, caused by transformed nanohtml tests
+  (function () {
+    document.createElement = function () {
+      optionsArg = arguments[1]
+      return originalCreateElement.apply(this, arguments)
+    }
+  })()
+
+  ;html`<div is="my-div"></div>`
+
+  t.ok(typeof optionsArg === 'object' && optionsArg.is === 'my-div', 'properly passes optional extends object')
+
+  // revert to original prototype method
+  delete document.createElement
+
+  t.end()
+})

tests/transform/index.js

@@ -6,8 +6,8 @@ var path = require('path')
 var FIXTURE = path.join(__dirname, 'fixture.js')
 
 test('works', function (t) {
-  t.plan(4)
-  var src = 'var html = require(\'nanohtml\')\n  module.exports = function (data) {\n    var className = \'test\'\n    return html`<div class="${className}">\n      <h1>${data}</h1>\n    </div>`\n  }' // eslint-disable-line
+  t.plan(5)
+  var src = 'var html = require(\'nanohtml\')\n  module.exports = function (data) {\n    var className = \'test\'\n    return html`<div class="${className}">\n      <h1>${data}</h1>\n   <div is="my-div"></div>    </div>`\n  }' // eslint-disable-line
   fs.writeFileSync(FIXTURE, src)
   var b = browserify(FIXTURE, {
     browserField: false,
@@ -19,6 +19,7 @@ test('works', function (t) {
     var result = src.toString()
     t.ok(result.indexOf('var html = {}') !== -1, 'replaced html dependency with {}')
     t.ok(result.indexOf('document.createElement("h1")') !== -1, 'created an h1 tag')
+    t.ok(result.indexOf('document.createElement("div", { is: "my-div" })') !== -1, 'created an extended build-in element')
     t.ok(result.indexOf('setAttribute("class", arguments[1])') !== -1, 'set a class attribute')
     t.end()
   })