avoid adding double colon (#315)

* avoid adding double colon

* Create beige-starfishes-worry.md

Author: JoviDeCroock

.changeset/beige-starfishes-worry.md

@@ -0,0 +1,5 @@
+---
+"preact-render-to-string": patch
+---
+
+avoid adding double colon for namespaced attributes

src/util.js

@@ -1,6 +1,6 @@
 export const VOID_ELEMENTS = /^(?:area|base|br|col|embed|hr|img|input|link|meta|param|source|track|wbr)$/;
 export const UNSAFE_NAME = /[\s\n\\/='"\0<>]/;
-export const NAMESPACE_REPLACE_REGEX = /^(xlink|xmlns|xml)(:|[A-Z])/;
+export const NAMESPACE_REPLACE_REGEX = /^(xlink|xmlns|xml)([A-Z])/;
 export const HTML_LOWER_CASE = /^accessK|^auto[A-Z]|^ch|^col|cont|cross|dateT|encT|form[A-Z]|frame|hrefL|inputM|maxL|minL|noV|playsI|readO|rowS|spellC|src[A-Z]|tabI|item[A-Z]/;
 export const SVG_CAMEL_CASE = /^ac|^ali|arabic|basel|cap|clipPath$|clipRule$|color|dominant|enable|fill|flood|font|glyph[^R]|horiz|image|letter|lighting|marker[^WUH]|overline|panose|pointe|paint|rendering|shape|stop|strikethrough|stroke|text[^L]|transform|underline|unicode|units|^v[^i]|^w|^xH/;
 

test/render.test.js

@@ -337,6 +337,12 @@ describe('render', () => {
 				`<svg><image xlink:href="#"></image><foreignObject><div xlink:href="#"></div></foreignObject><g><image xlink:href="#"></image></g></svg>`
 			);
 		});
+
+		it('should not add extra colon on SVG elements', () => {
+			let rendered = render(<svg>{h('image', { 'xlink:href': '#' })}</svg>);
+
+			expect(rendered).to.equal(`<svg><image xlink:href="#"></image></svg>`);
+		});
 	});
 
 	describe('Functional Components', () => {