dataToNamedExports helper

README.md

@@ -103,6 +103,30 @@ makeLegalIdentifier( 'foo-bar' ); // 'foo_bar'
 makeLegalIdentifier( 'typeof' ); // '_typeof'
 ```
 
+### dataToEsm
+
+Helper for treeshakable data imports
+
+```js
+import { dataToEsm } from 'rollup-pluginutils';
+
+const esModuleSource = dataToEsm({
+  custom: 'data',
+  to: ['treeshake']
+}, options = {
+  compact: false,
+  indent: '\t',
+  preferConst: false,
+  objectShorthand: false
+});
+/*
+Outputs the string ES module source:
+  export const custom = 'data';
+  export const to = ['treeshake'];
+  export default { custom, to };
+*/
+```
+
 
 ## License
 

package.json

@@ -24,7 +24,8 @@
   },
   "dependencies": {
     "estree-walker": "^0.3.0",
-    "micromatch": "^2.3.11"
+    "micromatch": "^2.3.11",
+    "tosource": "^1.0.0"
   },
   "repository": "rollup/rollup-pluginutils",
   "keywords": [

rollup.config.js

@@ -4,7 +4,7 @@ import buble from 'rollup-plugin-buble';
 export default {
 	entry: 'src/index.js',
 	plugins: [ buble() ],
-	external: [ 'path', 'estree-walker', 'micromatch' ],
+	external: [ 'path', 'estree-walker', 'micromatch', 'tosource' ],
 
 	targets: [
 		{

src/dataToEsm.js

@@ -0,0 +1,27 @@
+import makeLegalIdentifier from './makeLegalIdentifier';
+import tosource from 'tosource';
+
+// convert data object into separate named exports (and default)
+export default function dataToNamedExports ( data, options = {} ) {
+  const t = options.compact ? '' : 'indent' in options ? options.indent : '\t';
+  const _ = options.compact ? '' : ' ';
+  const n = options.compact ? '' : '\n';
+  const declarationType = options.preferConst ? 'const' : 'var';
+
+  let namedExportCode = '';
+  const defaultExportRows = [];
+  const dataKeys = Object.keys( data );
+  for (let i = 0; i < dataKeys.length; i++) {
+    const key = dataKeys[i];
+  	if (key === makeLegalIdentifier( key )) {
+      if ( options.objectShorthand )
+        defaultExportRows.push(key);
+      else
+  		  defaultExportRows.push( `${ key }:${ _ }${ key }` );
+  		namedExportCode += `export ${declarationType} ${key}${ _ }=${ _ }${ tosource( data[key], null, options.compact ? false : t ) };${ n }`;
+  	} else {
+      defaultExportRows.push( `${ JSON.stringify(key) }: ${ tosource( data[key], null, options.compact ? false : t )}` );
+    }
+  }
+  return namedExportCode + `export default${ _ }{${ n }${ t }${ defaultExportRows.join(`,${ n }${ t }`) }${ n }};${ n }`;
+};

src/index.js

@@ -2,3 +2,4 @@ export { default as addExtension } from './addExtension';
 export { default as attachScopes } from './attachScopes';
 export { default as createFilter } from './createFilter';
 export { default as makeLegalIdentifier } from './makeLegalIdentifier';
+export { default as dataToEsm } from './dataToEsm';

test/test.js

@@ -442,4 +442,26 @@ describe( 'rollup-pluginutils', function () {
 			assert.equal( makeLegalIdentifier( 'arguments' ), '_arguments' );
 		});
 	});
+
+	describe( 'dataToEsm', function () {
+		var dataToEsm = utils.dataToEsm;
+
+		it( 'outputs treeshakable data', function () {
+			assert.equal( dataToEsm( { some: 'data', another: 'data' } ), 'export var some = "data";\nexport var another = "data";\nexport default {\n\tsome: some,\n\tanother: another\n};\n' );
+		});
+
+		it( 'handles illegal identifiers, object shorthand, preferConst', function () {
+			assert.equal( dataToEsm( { '1': 'data', 'default': 'data' }, { objectShorthand: true, preferConst: true } ), 'export default {\n\t"1": "data",\n\t"default": "data"\n};\n' );
+		});
+
+		it( 'supports non-JSON data', function () {
+			const date = new Date();
+			assert.equal( dataToEsm( { inf: Infinity, date: date } ), 'export var inf = Infinity;\nexport var date = new Date(' + date.getTime() + ');\nexport default {\n\tinf: inf,\n\tdate: date\n};\n' );
+		});
+
+		it( 'supports a compact argument', function () {
+			assert.equal( dataToEsm( { some: 'data', another: 'data' }, { compact: true, objectShorthand: true } ), 'export var some="data";export var another="data";export default{some,another};' );
+			assert.equal( dataToEsm( { some: { deep: { object: 'definition', here: 'here' } }, another: 'data' }, { compact: true, objectShorthand: false } ), 'export var some={deep:{object:"definition",here:"here"}};export var another="data";export default{some:some,another:another};' );
+		});
+	});
 });