Repository: sveltejs/svelte (JavaScript) — Bug Fix

Issue:
SVG data attributes cause error in Edge
Hi, 
This example does not work in Edge:
https://svelte.technology/repl?version=1.44.2&gist=9c6e3507010663c0ef9e41901736c321

The problem was the attribute `data-name`. By removing it, I got the component to work in Edge. The error it gave was "Cannot set name on undefined or null reference".

TLDR:
SVGs in components with data-xxx attributes seem to not work in Edge. See here for why: 
[https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/data-*](https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/data-*)


```
<p class="footer-text">
            <svg class="footer-cart" xmlns="http://www.w3.org/2000/svg"
								 data-name="This attribute destroyed X-mas!"
             viewBox="0 0 55.8 48.6">
                <title>
                    cart_outline
                </title>
                <path class="cls-1" d="M54.8 16.3H13.6a1 1 0 0 1 0-2H54.8a1 1 0 1 1 0 2Z" ></path>
                <path class="cls-1" d="M47.6 37.9H18.9a1 1 0 0 1-1-0.8L9.2 2H1A1 1 0 0 1 1 0h9a1 1 0 0 1 1 0.8l8.8 35.1H47.6a1 1 0 0 1 0 2Z" ></path>
                <path class="cls-1" d="M20.7 48.6A4.6 4.6 0 1 1 25.3 44 4.6 4.6 0 0 1 20.7 48.6Zm0-7.2A2.6 2.6 0 1 0 23.3 44 2.6 2.6 0 0 0 20.7 41.5Z" ></path>
                <path class="cls-1" d="M44 48.6A4.6 4.6 0 1 1 48.6 44 4.6 4.6 0 0 1 44 48.6Zm0-7.2A2.6 2.6 0 1 0 46.6 44 2.6 2.6 0 0 0 44 41.5Z" ></path>
                <path class="cls-1" d="M52.4 23.6H22.5a1 1 0 0 1 0-2H52.4a1 1 0 0 1 0 2Z" ></path>
                <path class="cls-1" d="M50 30.7H24.3a1 1 0 0 1 0-2H50a1 1 0 1 1 0 2Z" ></path>
	</svg></p>
```



Discussion:

Resolving patch:
diff --git a/src/generators/nodes/Attribute.ts b/src/generators/nodes/Attribute.ts
--- a/src/generators/nodes/Attribute.ts
+++ b/src/generators/nodes/Attribute.ts
@@ -83,7 +83,7 @@ export default class Attribute {
 
 		const isLegacyInputType = this.generator.legacy && name === 'type' && this.parent.name === 'input';
 
-		const isDataSet = /^data-/.test(name) && !this.generator.legacy;
+		const isDataSet = /^data-/.test(name) && !this.generator.legacy && !node.namespace;
 		const camelCaseName = isDataSet ? name.replace('data-', '').replace(/(-\w)/g, function (m) {
 			return m[1].toUpperCase();
 		}) : name;


Test patch:
diff --git a/test/js/samples/dont-use-dataset-in-svg/expected-bundle.js b/test/js/samples/dont-use-dataset-in-svg/expected-bundle.js
new file mode 100644
--- /dev/null
+++ b/test/js/samples/dont-use-dataset-in-svg/expected-bundle.js
@@ -0,0 +1,242 @@
+function noop() {}
+
+function assign(target) {
+	var k,
+		source,
+		i = 1,
+		len = arguments.length;
+	for (; i < len; i++) {
+		source = arguments[i];
+		for (k in source) target[k] = source[k];
+	}
+
+	return target;
+}
+
+function appendNode(node, target) {
+	target.appendChild(node);
+}
+
+function insertNode(node, target, anchor) {
+	target.insertBefore(node, anchor);
+}
+
+function detachNode(node) {
+	node.parentNode.removeChild(node);
+}
+
+function createSvgElement(name) {
+	return document.createElementNS('http://www.w3.org/2000/svg', name);
+}
+
+function setAttribute(node, attribute, value) {
+	node.setAttribute(attribute, value);
+}
+
+function blankObject() {
+	return Object.create(null);
+}
+
+function destroy(detach) {
+	this.destroy = noop;
+	this.fire('destroy');
+	this.set = this.get = noop;
+
+	if (detach !== false) this._fragment.u();
+	this._fragment.d();
+	this._fragment = this._state = null;
+}
+
+function differs(a, b) {
+	return a !== b || ((a && typeof a === 'object') || typeof a === 'function');
+}
+
+function dispatchObservers(component, group, changed, newState, oldState) {
+	for (var key in group) {
+		if (!changed[key]) continue;
+
+		var newValue = newState[key];
+		var oldValue = oldState[key];
+
+		var callbacks = group[key];
+		if (!callbacks) continue;
+
+		for (var i = 0; i < callbacks.length; i += 1) {
+			var callback = callbacks[i];
+			if (callback.__calling) continue;
+
+			callback.__calling = true;
+			callback.call(component, newValue, oldValue);
+			callback.__calling = false;
+		}
+	}
+}
+
+function fire(eventName, data) {
+	var handlers =
+		eventName in this._handlers && this._handlers[eventName].slice();
+	if (!handlers) return;
+
+	for (var i = 0; i < handlers.length; i += 1) {
+		handlers[i].call(this, data);
+	}
+}
+
+function get(key) {
+	return key ? this._state[key] : this._state;
+}
+
+function init(component, options) {
+	component._observers = { pre: blankObject(), post: blankObject() };
+	component._handlers = blankObject();
+	component._root = options._root || component;
+	component._bind = options._bind;
+
+	component.options = options;
+	component.store = component._root.options.store;
+}
+
+function observe(key, callback, options) {
+	var group = options && options.defer
+		? this._observers.post
+		: this._observers.pre;
+
+	(group[key] || (group[key] = [])).push(callback);
+
+	if (!options || options.init !== false) {
+		callback.__calling = true;
+		callback.call(this, this._state[key]);
+		callback.__calling = false;
+	}
+
+	return {
+		cancel: function() {
+			var index = group[key].indexOf(callback);
+			if (~index) group[key].splice(index, 1);
+		}
+	};
+}
+
+function on(eventName, handler) {
+	if (eventName === 'teardown') return this.on('destroy', handler);
+
+	var handlers = this._handlers[eventName] || (this._handlers[eventName] = []);
+	handlers.push(handler);
+
+	return {
+		cancel: function() {
+			var index = handlers.indexOf(handler);
+			if (~index) handlers.splice(index, 1);
+		}
+	};
+}
+
+function set(newState) {
+	this._set(assign({}, newState));
+	if (this._root._lock) return;
+	this._root._lock = true;
+	callAll(this._root._beforecreate);
+	callAll(this._root._oncreate);
+	callAll(this._root._aftercreate);
+	this._root._lock = false;
+}
+
+function _set(newState) {
+	var oldState = this._state,
+		changed = {},
+		dirty = false;
+
+	for (var key in newState) {
+		if (differs(newState[key], oldState[key])) changed[key] = dirty = true;
+	}
+	if (!dirty) return;
+
+	this._state = assign({}, oldState, newState);
+	this._recompute(changed, this._state);
+	if (this._bind) this._bind(changed, this._state);
+
+	if (this._fragment) {
+		dispatchObservers(this, this._observers.pre, changed, this._state, oldState);
+		this._fragment.p(changed, this._state);
+		dispatchObservers(this, this._observers.post, changed, this._state, oldState);
+	}
+}
+
+function callAll(fns) {
+	while (fns && fns.length) fns.pop()();
+}
+
+function _mount(target, anchor) {
+	this._fragment.m(target, anchor);
+}
+
+function _unmount() {
+	this._fragment.u();
+}
+
+var proto = {
+	destroy: destroy,
+	get: get,
+	fire: fire,
+	observe: observe,
+	on: on,
+	set: set,
+	teardown: destroy,
+	_recompute: noop,
+	_set: _set,
+	_mount: _mount,
+	_unmount: _unmount
+};
+
+/* generated by Svelte vX.Y.Z */
+function create_main_fragment(state, component) {
+	var svg, g, g_1;
+
+	return {
+		c: function create() {
+			svg = createSvgElement("svg");
+			g = createSvgElement("g");
+			g_1 = createSvgElement("g");
+			this.h();
+		},
+
+		h: function hydrate() {
+			setAttribute(g, "data-foo", "bar");
+			setAttribute(g_1, "data-foo", state.bar);
+		},
+
+		m: function mount(target, anchor) {
+			insertNode(svg, target, anchor);
+			appendNode(g, svg);
+			appendNode(g_1, svg);
+		},
+
+		p: function update(changed, state) {
+			if (changed.bar) {
+				setAttribute(g_1, "data-foo", state.bar);
+			}
+		},
+
+		u: function unmount() {
+			detachNode(svg);
+		},
+
+		d: noop
+	};
+}
+
+function SvelteComponent(options) {
+	init(this, options);
+	this._state = assign({}, options.data);
+
+	this._fragment = create_main_fragment(this._state, this);
+
+	if (options.target) {
+		this._fragment.c();
+		this._fragment.m(options.target, options.anchor || null);
+	}
+}
+
+assign(SvelteComponent.prototype, proto);
+
+export default SvelteComponent;
diff --git a/test/js/samples/dont-use-dataset-in-svg/expected.js b/test/js/samples/dont-use-dataset-in-svg/expected.js
new file mode 100644
--- /dev/null
+++ b/test/js/samples/dont-use-dataset-in-svg/expected.js
@@ -0,0 +1,53 @@
+/* generated by Svelte vX.Y.Z */
+import { appendNode, assign, createSvgElement, detachNode, init, insertNode, noop, proto, setAttribute } from "svelte/shared.js";
+
+function create_main_fragment(state, component) {
+	var svg, g, g_1;
+
+	return {
+		c: function create() {
+			svg = createSvgElement("svg");
+			g = createSvgElement("g");
+			g_1 = createSvgElement("g");
+			this.h();
+		},
+
+		h: function hydrate() {
+			setAttribute(g, "data-foo", "bar");
+			setAttribute(g_1, "data-foo", state.bar);
+		},
+
+		m: function mount(target, anchor) {
+			insertNode(svg, target, anchor);
+			appendNode(g, svg);
+			appendNode(g_1, svg);
+		},
+
+		p: function update(changed, state) {
+			if (changed.bar) {
+				setAttribute(g_1, "data-foo", state.bar);
+			}
+		},
+
+		u: function unmount() {
+			detachNode(svg);
+		},
+
+		d: noop
+	};
+}
+
+function SvelteComponent(options) {
+	init(this, options);
+	this._state = assign({}, options.data);
+
+	this._fragment = create_main_fragment(this._state, this);
+
+	if (options.target) {
+		this._fragment.c();
+		this._fragment.m(options.target, options.anchor || null);
+	}
+}
+
+assign(SvelteComponent.prototype, proto);
+export default SvelteComponent;
\ No newline at end of file
diff --git a/test/js/samples/dont-use-dataset-in-svg/input.html b/test/js/samples/dont-use-dataset-in-svg/input.html
new file mode 100644
--- /dev/null
+++ b/test/js/samples/dont-use-dataset-in-svg/input.html
@@ -0,0 +1,4 @@
+<svg>
+	<g data-foo='bar'/>
+	<g data-foo='{{bar}}'/>
+</svg>