feat: add handlebar helper prefixModuleScript

Author: falric

README.md

@@ -40,6 +40,7 @@ Usage in templates:
 - {{ withVersion url }} -- appends `'?v=' + version` to the passed string
 - {{ extend name options }} -- calls the function options.fn with content of block **name** as param and adds it to named block
 - {{ prefixScript url name }} -- add a script tag with version set to script block **name**
+- {{ prefixModuleScript url name }} -- add a script tag with type module and with version set to script block **name**
 - {{ prefixStyle url name media }} -- add a style tag for named media type with version set to style block **name**
 - {{ render name }} -- used by a layout to render script and style blocks in appropriate places
 

lib/handlebars/helpers/headerContent.js

@@ -87,6 +87,30 @@ module.exports = function headerContent(options) {
     _blocks[blockName].push(`<script src="${url}"></script>`)
   })
 
+  /** @function prefixModuleScript
+   *
+   * @param {string} url -- local path to script excluding proxyPrefixPath
+   * @param {string} blockName -- (optional) name of script block to include with, defaults to 'scripts'
+   *
+   * @return output with {{ render blockName }}
+   *
+   * @example
+   * {{prefixModuleScript '/path/to/script.js' 'scripts'}}
+   */
+  Handlebars.registerHelper('prefixModuleScript', function prefixModuleScript(urlIn, blockNameIn) {
+    // Check params and give useful error message since stack traces aren't very useable in layouts
+    if (typeof urlIn !== 'string') {
+      throw new Error('[prefixModuleScript] helper requires first parameter (url) to be a string. Got: ' + urlIn)
+    }
+
+    const blockName = typeof blockNameIn === 'string' ? blockNameIn : 'scripts'
+    _blocks[blockName] = _blocks[blockName] || []
+
+    const url = `${proxyPrefixPathUri}${urlIn}?v=${encodeURIComponent(version)}`
+
+    _blocks[blockName].push(`<script type="module" src="${url}"></script>`)
+  })
+
   /** @function prefixStyle
    *
    * @param {string} url -- local path to script excluding proxyPrefixPath