feat(removeUnknownAndDefaults): apply to xml declarations (#1872)

docs/03-plugins/remove-unknowns-and-defaults.mdx

@@ -13,6 +13,9 @@ svgo:
  defaultAttrs:
  description: If to remove attributes that are assigned their default value anyway.
  default: true
+ defaultMarkupDeclarations:
+ description: If to remove XML declarations that are assigned their default value. XML declarations are the properties in the <code>&lt;?xml … ?&gt;</code> block at the top of the document.
+ default: true
  uselessOverrides:
  description: If to remove attributes that are being if the same value is being inherited by it's parent element anyway.
  default: true
@@ -29,6 +32,8 @@ svgo:
 
 Removes unknown elements and attributes, as well as attributes that are set to their default value.
 
+This can also remove defaults from the XML declaration if present in the document, namely [`standalone`](https://www.w3.org/TR/REC-xml/#sec-rmd) if it's set to `no`.
+
 ## Usage
 
 <PluginUsage/>

docs/03-plugins/remove-xml-proc-inst.mdx

@@ -17,7 +17,7 @@ An XML declaration is the line at the top of an XML file to indicate document me
 
 The XML declaration is optional in [XML 1.0](https://www.w3.org/TR/REC-xml/#sec-prolog-dtd), but mandatory in the [XML 1.1](https://www.w3.org/TR/2006/REC-xml11-20060816/#sec-prolog-dtd). If the XML declaration is omitted, the document is assumed to follow the XML 1.0 specifications, which won't impact SVG documents.
 
-It can be safely removed without impacting compatibility.
+It can be safely removed without impacting compatibility with SVG clients. However, some tools may fail to detect the MIME-type as `image/svg+xml` if this is removed.
 
 ## Usage
 

plugins/plugins-types.d.ts

@@ -14,8 +14,8 @@ type DefaultPlugins = {
  cleanupIds: {
  remove?: boolean;
  minify?: boolean;
- preserve?: Array<string>;
- preservePrefixes?: Array<string>;
+ preserve?: string[];
+ preservePrefixes?: string[];
  force?: boolean;
  };
  cleanupNumericValues: {
@@ -146,7 +146,7 @@ type DefaultPlugins = {
  };
  removeDoctype: void;
  removeEditorsNSData: {
- additionalNamespaces?: Array<string>;
+ additionalNamespaces?: string[];
  };
  removeEmptyAttrs: void;
  removeEmptyContainers: void;
@@ -179,6 +179,12 @@ type DefaultPlugins = {
  unknownContent?: boolean;
  unknownAttrs?: boolean;
  defaultAttrs?: boolean;
+ /**
+ * If to remove XML declarations that are assigned their default value. XML
+ * declarations are the properties in the `<?xml … ?>` block at the top of
+ * the document.
+ */
+ defaultMarkupDeclarations?: boolean;
  uselessOverrides?: boolean;
  keepDataAttrs?: boolean;
  keepAriaAttrs?: boolean;
@@ -194,7 +200,7 @@ type DefaultPlugins = {
  removeViewBox: void;
  removeXMLProcInst: void;
  sortAttrs: {
- order?: Array<string>;
+ order?: string[];
  xmlnsOrder?: 'front' | 'alphabetical';
  };
  sortDefsChildren: void;
@@ -262,17 +268,17 @@ export type BuiltinsWithRequiredParams = {
  };
  addClassesToSVGElement: {
  className?: string;
- classNames?: Array<string>;
+ classNames?: string[];
  };
  removeAttributesBySelector: any;
  removeAttrs: {
  elemSeparator?: string;
  preserveCurrentColor?: boolean;
- attrs: string | Array<string>;
+ attrs: string | string[];
  };
  removeElementsByAttr: {
- id?: string | Array<string>;
- class?: string | Array<string>;
+ id?: string | string[];
+ class?: string | string[];
  };
 };
 

plugins/removeUnknownsAndDefaults.js

@@ -99,6 +99,7 @@ exports.fn = (root, params) => {
  unknownContent = true,
  unknownAttrs = true,
  defaultAttrs = true,
+ defaultMarkupDeclarations = true,
  uselessOverrides = true,
  keepDataAttrs = true,
  keepAriaAttrs = true,
@@ -107,6 +108,13 @@ exports.fn = (root, params) => {
  const stylesheet = collectStylesheet(root);
 
  return {
+ instruction: {
+ enter: (node) => {
+ if (defaultMarkupDeclarations) {
+ node.value = node.value.replace(/\s*standalone\s*=\s*(["'])no\1/, '');
+ }
+ },
+ },
  element: {
  enter: (node, parentNode) => {
  // skip namespaced elements