feat: support 'before' insertions (options.insertAt) (#253)

iancw · michael-ciniawsky · commit 67120f8dc831 · 2017-09-09T01:56:21.000+02:00
diff --git a/README.md b/README.md
@@ -137,7 +137,7 @@ Styles are not added on `import/require()`, but instead on call to `use`/`ref`.
 |**`base`** |`{Number}`|`true`|Set module ID base (DLLPlugin)|
 |**`attrs`**|`{Object}`|`{}`|Add custom attrs to `<style></style>`|
 |**`transform`** |`{Function}`|`false`|Transform/Conditionally load CSS by passing a transform/condition function|
-|**`insertAt`**|`{String}`|`bottom`|Inserts `<style></style>` at the given position|
+|**`insertAt`**|`{String\|Object}`|`bottom`|Inserts `<style></style>` at the given position|
 |**`insertInto`**|`{String}`|`<head>`|Inserts `<style></style>` into the given position|
 |**`sourceMap`**|`{Boolean}`|`false`|Enable/Disable Sourcemaps|
 |**`convertToAbsoluteUrls`**|`{Boolean}`|`false`|Converts relative URLs to absolute urls, when source maps are enabled|
@@ -285,6 +285,20 @@ By default, the style-loader appends `<style>` elements to the end of the style
 }
 ```
 
+A new `<style>` element can be inserted before a specific element by passing an object, e.g.
+
+**webpack.config.js**
+```js
+{
+  loader: 'style-loader'
+  options: {
+    insertAt: {
+        before: '#id'
+    }
+  }
+}
+```
+
 ### `insertInto`
 By default, the style-loader inserts the `<style>` elements into the `<head>` tag of the page. If you want the tags to be inserted somewhere else you can specify a CSS selector for that element here. If you target an [IFrame](https://developer.mozilla.org/en-US/docs/Web/API/HTMLIFrameElement) make sure you have sufficient access rights, the styles will be injected into the content document head.
 You can also insert the styles into a [ShadowRoot](https://developer.mozilla.org/en-US/docs/Web/API/ShadowRoot), e.g
diff --git a/lib/addStyles.js b/lib/addStyles.js
@@ -170,8 +170,11 @@ function insertStyleElement (options, style) {
 		stylesInsertedAtTop.push(style);
 	} else if (options.insertAt === "bottom") {
 		target.appendChild(style);
+	} else if (typeof options.insertAt === "object" && options.insertAt.before) {
+		var nextSibling = getElement(options.insertInto + " " + options.insertAt.before);
+		target.insertBefore(style, nextSibling);
 	} else {
-		throw new Error("Invalid value for parameter 'insertAt'. Must be 'top' or 'bottom'.");
+		throw new Error("[Style Loader]\n\n Invalid value for parameter 'insertAt' ('options.insertAt') found.\n Must be 'top', 'bottom', or Object.\n (https://github.com/webpack-contrib/style-loader#insertat)\n");
 	}
 }
 
diff --git a/options.json b/options.json
@@ -9,7 +9,7 @@
       "type": "object"
     },
     "insertAt": {
-      "type": "string"
+      "type": ["string", "object"]
     },
     "insertInto": {
       "type": "string"
diff --git a/test/basicTest.js b/test/basicTest.js
@@ -19,7 +19,7 @@ describe("basic tests", function() {
       }
     `,
     requiredStyle = `<style type="text/css">${requiredCss}</style>`,
-    existingStyle = "<style>.existing { color: yellow }</style>",
+    existingStyle = `<style id="existing-style">.existing { color: yellow }</style>`,
     checkValue = '<div class="check">check</div>',
     rootDir = path.resolve(__dirname + "/../") + "/",
     jsdomHtml = [
@@ -95,6 +95,26 @@ describe("basic tests", function() {
     runCompilerTest(expected, done);
   }); // it insert at top
 
+  it("insert at before", function(done) {
+    styleLoaderOptions.insertAt = {
+        before: "#existing-style"
+    };
+
+    let expected = [requiredStyle, existingStyle].join("");
+
+    runCompilerTest(expected, done);
+  }); // it insert at before
+
+  it("insert at before invalid selector", function(done) {
+    styleLoaderOptions.insertAt = {
+        before: "#missing"
+    };
+
+    let expected = [existingStyle, requiredStyle].join("\n");
+
+    runCompilerTest(expected, done);
+  }); // it insert at before
+
   it("insert into", function(done) {
     let selector = "div.target";
     styleLoaderOptions.insertInto = selector;

Original file line number	Diff line number	Diff line change
`@@ -170,8 +170,11 @@ function insertStyleElement (options, style) {`
`170`	`170`	`stylesInsertedAtTop.push(style);`
`171`	`171`	`} else if (options.insertAt === "bottom") {`
`172`	`172`	`target.appendChild(style);`
	`173`	`+ } else if (typeof options.insertAt === "object" && options.insertAt.before) {`
	`174`	`+ var nextSibling = getElement(options.insertInto + " " + options.insertAt.before);`
	`175`	`+ target.insertBefore(style, nextSibling);`
`173`	`176`	`} else {`
`174`		`- throw new Error("Invalid value for parameter 'insertAt'. Must be 'top' or 'bottom'.");`
	`177`	`+ throw new Error("[Style Loader]\n\n Invalid value for parameter 'insertAt' ('options.insertAt') found.\n Must be 'top', 'bottom', or Object.\n (https://github.com/webpack-contrib/style-loader#insertat)\n");`
`175`	`178`	`}`
`176`	`179`	`}`
`177`	`180`