- Added missingLocal option to define how to handle and produce in case of missing local value

- `ignoreTag` will not remove the tag itself if it is simple like `<input>`

Author: b-gyula

lib/index.js

@@ -161,7 +161,15 @@ module.exports = function postHTMLExpressions (options) {
   return function (tree) {
     const { locals } = scriptDataLocals(tree, options)
 
-    return normalizeTree(clearRawTag(walk({ locals: { ...options.locals, ...locals }, strictMode: options.strictMode }, tree)), tree.options)
+    return normalizeTree(
+      clearRawTag(
+        walk(
+          {
+            locals: { ...options.locals, ...locals },
+            strictMode: options.strictMode,
+            missingLocal: options.missingLocal
+          }, tree)
+      ), tree.options)
   }
 }
 
@@ -430,12 +438,10 @@ function clearRawTag (tree) {
   return tree.reduce((m, node) => {
     if (node.content) {
       node.content = clearRawTag(node.content)
+      if (node.tag === ignored) {
+        node.tag = false
+      }
     }
-
-    if (node.tag === ignored) {
-      node.tag = false
-    }
-
     m.push(node)
 
     return m

lib/placeholders.js

@@ -66,13 +66,20 @@ function placeholders (input, ctx, settings, opts) {
         value = ctx[expression]
       }
 
+      // Not found local
+      if (value === null || value === undefined) {
+        if (opts.missingLocal === undefined) {
+          if (opts.strictMode) {
+            throw new ReferenceError(`'${expression}' is not defined`)
+          }
+        } else if (typeof opts.missingLocal === 'string') {
+          value = opts.missingLocal.replace('{expression}', match)
+        }
+      }
       // Escape html if necessary
       if (settings[i].escape && typeof value === 'string') {
         value = escapeHTML(value)
-      }
-
-      // Stringify if value object
-      if (typeof value === 'object') {
+      } else if (typeof value === 'object') { // Stringify if value object
         value = JSON.stringify(value)
       }
 

readme.md

@@ -37,17 +37,18 @@ You have full control over the delimiters used for injecting locals, as well as
 
 |Option|Default|Description|
 |:----:|:-----:|:----------|
-| **delimiters** | `['{{', '}}']` | Array containing beginning and ending delimiters for escaped locals |
-| **unescapeDelimiters** | `['{{{', '}}}']` | Array containing beginning and ending delimiters for unescaped locals |
-| **locals** | `{}` | Object containing any local variables you want to be available inside your expressions |
+| **delimiters** | `['{{', '}}']` | Array containing beginning and ending delimiters for escaped locals os [expressions](#expressions) |
+| [**unescapeDelimiters**](#unescaped-locals) | `['{{{', '}}}']` | Array containing beginning and ending delimiters for unescaped locals |
+| [**locals**](#locals) | `{}` | Object containing any local variables you want to be available inside your expressions |
 | **localsAttr** | `locals` | Attribute name for the tag `script` which contains ***[locals](#locals)***|
 | **removeScriptLocals** | `false` | Will remove tag `script` which contains ***[locals](#locals)***|
-| **conditionalTags** | `['if', 'elseif', 'else']` | Array containing names for tags used for `if/else if/else` statements |
-| **switchTags** | `['switch', 'case', 'default']` | Array containing names for tags used for `switch/case/default` statements |
+| [**conditionalTags**](#conditionals) | `['if', 'elseif', 'else']` | Array containing names for tags used for [*`if/else` statements*](#conditionals) |
+| [**switchTags**](#switchtags) | `['switch', 'case', 'default']` | Array containing names for tags used for [*`switch/case/default` statements*](#switch-statement) |
 | **loopTags** | `['each']` | Array containing names for `for` loops |
 | **scopeTags** | `['scope']` | Array containing names for scopes |
-| **ignoredTag** | `'raw'` | String containing name of tag inside which parsing is disabled |
-| **strictMode** | `true` | Boolean value set to `false` will not throw an exception |
+| [**ignoredTag**](#ignored-tag) | `'raw'` | String containing name of tag inside which parsing is disabled |
+| **strictMode** | `true` | Boolean value set to `false` will not throw an exception if a value in locals not found or expression could not be evaluated|
+| [**missingLocal**](#missing-locals) | `undefined` | string defining the replacement value in case value not found in locals. May contain `{expression}` placeholder|
 
 ### Locals
 
@@ -124,6 +125,15 @@ posthtml(expressions({ locals: { foo: 'bar' } }))
 <div>My name: {{name}}</div>
 <div>Foo: bar</div>
 ```
+#### Missing locals
+What to produce in case of referencing a value not in locals can be configured by the `missingLocal` and `strictMode` options
+
+|`missingLocal`|`strictMode`|output|
+|:----:|:-----:|:----------|
+| `undefined` (default) | `true` (default) | Error is thrown |
+| `undefined` (default) | `false` | 'undefined' |
+| `''` | `false`/`true` | `''` (not output)
+| `{expression}` | `false`/`true` | [original local] like {{foo}}
 
 ### Unescaped Locals
 

test/expect/local_missing.html

@@ -0,0 +1 @@
+<p>undefined<b>undefined</b></p>

test/expect/local_missing_keep.html

@@ -0,0 +1 @@
+<p>{{foo}}</p>

test/expect/local_missing_remove.html

@@ -0,0 +1 @@
+<p><b></b></p>

test/expect/local_missing_replace.html

@@ -0,0 +1 @@
+<p>Error: {{foo}} undefined</p>

test/fixtures/local_missing.html

@@ -0,0 +1 @@
+<p>{{foo}}<b>{{foo? "bar": ""}}</b></p>

test/fixtures/local_missing_keep.html

@@ -0,0 +1 @@
+<p>{{foo}}</p>

test/fixtures/local_missing_remove.html

@@ -0,0 +1 @@
+<p>{{foo}}</p>