[Add] stripdeclarations option

Add the option `stripdeclarions` to the loader.
If given will tell the loader to strip out any XML declaration, e.g.

    <?xml version="1.0" encoding="UTF-8"?>

at the beginning of imported SVGs.

Added because Internet Explorer (tested in Edge 14) cannot handle XML
declarations in CSS data URLs (`content: url("data:image/svg...")`).

README.md

@@ -3,11 +3,11 @@
 
 A webpack loader which loads SVG file as utf-8 encoded DataUrl string.
 
-Existing [`url-loader`](https://github.com/webpack-contrib/url-loader) always does Base64 encoding for data-uri.  As SVG content is a human-readable xml string, using base64 encoding is not mandatory.  Instead, one may only escape [unsafe characters](http://www.ietf.org/rfc/rfc1738.txt) and replace `"` with `'` as described [in this article](http://codepen.io/Tigt/post/optimizing-svgs-in-data-uris).  
+Existing [`url-loader`](https://github.com/webpack-contrib/url-loader) always does Base64 encoding for data-uri.  As SVG content is a human-readable xml string, using base64 encoding is not mandatory.  Instead, one may only escape [unsafe characters](http://www.ietf.org/rfc/rfc1738.txt) and replace `"` with `'` as described [in this article](http://codepen.io/Tigt/post/optimizing-svgs-in-data-uris).
 
-There are some benefits for choosing utf-8 encoding over base64.  
-1. Resulting string is shorter (can be ~2 times shorter for 2K-sized icons);  
-2. Resulting string will be compressed better when using gzip compression;  
+There are some benefits for choosing utf-8 encoding over base64.
+1. Resulting string is shorter (can be ~2 times shorter for 2K-sized icons);
+2. Resulting string will be compressed better when using gzip compression;
 3. Browser parses utf-8 encoded string faster than its base64 equivalent.
 
 ## Supported parameters
@@ -23,8 +23,8 @@ Passing this parameter (or setting to `true`) tells to loader *not to include* r
 
 ### `limit`
 
-If given will tell the loader not to encode the source file if its content is greater than this limit.  
-Defaults to no limit.  
+If given will tell the loader not to encode the source file if its content is greater than this limit.
+Defaults to no limit.
 If the file is greater than the limit the [`file-loader`](https://github.com/webpack-contrib/file-loader) is used and all query parameters are passed to it.
 
 ``` javascript
@@ -36,6 +36,15 @@ require('svg-url-loader?prefix=img/!./file.svg');
 //    They are passed to the file-loader if used.
 ```
 
+### `stripdeclarations`
+
+If given will tell the loader to strip out any XML declaration, e.g. `<?xml version="1.0" encoding="UTF-8"?>` at the beginning of imported SVGs.
+Internet Explorer (tested in Edge 14) cannot handle XML declarations in CSS data URLs (`content: url("data:image/svg...")`).
+
+``` javascript
+require('svg-url-loader?stripdeclarations!./file.svg');
+```
+
 ## Usage
 
 [Documentation: Loaders](https://webpack.js.org/concepts/loaders/)

index.js

@@ -8,11 +8,16 @@ module.exports = function(content) {
 	this.cacheable && this.cacheable();
 
 	var query = loaderUtils.getOptions(this);
-	
+
 	var limit = query.limit ? parseInt(query.limit, 10) : 0;
-	
-	if(limit <= 0 || content.length < limit) {
+
+	if (limit <= 0 || content.length < limit) {
 		content = content.toString('utf8');
+
+		if (query.stripdeclarations) {
+			content = content.replace(/^\s*<\?xml [^>]*>\s*/i, "");
+		}
+
 		content = content.replace(/"/g, "'");
 		content = content.replace(/\s+/g, " ");
 		content = content.replace(/[{}\|\\\^~\[\]`"<>#%]/g, function(match) {

test/input/icon-with-declaration.js

@@ -0,0 +1,2 @@
+var icon = require('./images/icon-with-declaration.svg');
+module.exports = icon;

test/loader.spec.js

@@ -6,7 +6,7 @@ var webpack = require('webpack');
 
 describe('svg-url-loader', function() {
     'use strict';
-    
+
     this.timeout(10000);
 
     var outputDir = path.resolve(__dirname, './output'),
@@ -85,6 +85,65 @@ describe('svg-url-loader', function() {
     });
 
 
+    describe('"stripdeclarations" option', function () {
+        it('if turned off - should do nothing to an SVG that has an XML declaration', function(done) {
+            var config = assign({}, globalConfig, {
+                entry: './test/input/icon-with-declaration.js'
+            });
+            config.module.rules[0].use[0].options.stripdeclarations = false;
+
+            webpack(config, function(err) {
+                expect(err).to.be(null);
+                fs.readFile(getBundleFile(), function(err, data) {
+                    expect(err).to.be(null);
+                    var encoded = (0,eval)(data.toString());
+                    expect(encoded.indexOf("%3C?xml version='1.0' encoding='UTF-8'?%3E")).to.be.greaterThan(-1);
+                    return done();
+                });
+            });
+        });
+
+        it('if turned on - should do nothing to an SVG that doesn\'t have an XML declaration', function(done) {
+            var config = assign({}, globalConfig, {
+                entry: './test/input/icon.js'
+            });
+            config.module.rules[0].use[0].options.stripdeclarations = true;
+
+            webpack(config, function(err) {
+                expect(err).to.be(null);
+                fs.readFile(getBundleFile(), function(err, data) {
+                    expect(err).to.be(null);
+                    var encoded = (0,eval)(data.toString());
+                    expect(encoded.indexOf('"')).to.be(0);
+                    expect(encoded.lastIndexOf('"')).to.be(encoded.length - 1);
+                    expect(encoded.indexOf('data:image/svg+xml,%3Csvg')).to.be(1);
+                    return done();
+                });
+            });
+        });
+
+
+        it('if turned on - should remove XML declaration from a file that has one', function(done) {
+            var config = assign({}, globalConfig, {
+                entry: './test/input/icon-with-declaration.js'
+            });
+            config.module.rules[0].use[0].options.stripdeclarations = true;
+
+            webpack(config, function(err) {
+                expect(err).to.be(null);
+                fs.readFile(getBundleFile(), function(err, data) {
+                    expect(err).to.be(null);
+                    var encoded = (0,eval)(data.toString());
+                    expect(encoded.indexOf('%3C?xml version="1.0" encoding="UTF-8"?%3E')).to.be(-1);
+                    expect(encoded.indexOf('data:image/svg+xml,%3Csvg')).to.be(1);
+                    return done();
+                });
+            });
+        });
+    });
+
+
+
     describe('"limit" option and "url.dataUrlLimit" configuration', function () {
         it('should fall back to file-loader if the content of SVG file is longer than "limit" query parameter', function(done) {
             var config = assign({}, globalConfig, {