fix: Set element's value attribute to default empty string if nothing is provided

src/compiler/compile/render_dom/wrappers/Element/Attribute.ts

@@ -134,6 +134,11 @@ export default class AttributeWrapper extends BaseAttributeWrapper {
 		let updater: Node[];
 		const init = this.get_init(block, value);
 
+		// Set inputs value default to '' if undefined
+		if (name == 'value') {
+			block.chunks.mount.push(b`@set_input_value(${element.var}, ${value});`);
+		}
+
 		if (is_legacy_input_type) {
 			block.chunks.hydrate.push(
 				b`@set_input_type(${element.var}, ${init});`
@@ -149,6 +154,7 @@ export default class AttributeWrapper extends BaseAttributeWrapper {
 				updater = b`@select_option(${element.var}, ${value});`;
 			}
 
+
 			block.chunks.mount.push(b`
 				${updater}
 			`);

test/js/samples/input-default-value/expected.js

@@ -0,0 +1,85 @@
+/* generated by Svelte vX.Y.Z */
+import {
+	SvelteComponent,
+	append,
+	detach,
+	element,
+	init,
+	insert,
+	listen,
+	noop,
+	safe_not_equal,
+	set_data,
+	set_input_value,
+	space,
+	text
+} from "svelte/internal";
+
+function create_fragment(ctx) {
+	let input;
+	let t0;
+	let h1;
+	let t1;
+	let t2;
+	let mounted;
+	let dispose;
+
+	return {
+		c() {
+			input = element("input");
+			t0 = space();
+			h1 = element("h1");
+			t1 = text(/*name*/ ctx[0]);
+			t2 = text("!");
+			input.value = /*name*/ ctx[0];
+		},
+		m(target, anchor) {
+			insert(target, input, anchor);
+			set_input_value(input, /*name*/ ctx[0]);
+			insert(target, t0, anchor);
+			insert(target, h1, anchor);
+			append(h1, t1);
+			append(h1, t2);
+
+			if (!mounted) {
+				dispose = listen(input, "input", /*onInput*/ ctx[1]);
+				mounted = true;
+			}
+		},
+		p(ctx, [dirty]) {
+			if (dirty & /*name*/ 1 && input.value !== /*name*/ ctx[0]) {
+				input.value = /*name*/ ctx[0];
+			}
+
+			if (dirty & /*name*/ 1) set_data(t1, /*name*/ ctx[0]);
+		},
+		i: noop,
+		o: noop,
+		d(detaching) {
+			if (detaching) detach(input);
+			if (detaching) detach(t0);
+			if (detaching) detach(h1);
+			mounted = false;
+			dispose();
+		}
+	};
+}
+
+function instance($$self, $$props, $$invalidate) {
+	let name;
+
+	function onInput(event) {
+		$$invalidate(0, name = event.target.value);
+	}
+
+	return [name, onInput];
+}
+
+class Component extends SvelteComponent {
+	constructor(options) {
+		super();
+		init(this, options, instance, create_fragment, safe_not_equal, {});
+	}
+}
+
+export default Component;

test/js/samples/input-default-value/input.svelte

@@ -0,0 +1,11 @@
+<script>
+	let name ;
+
+	function onInput(event) {
+		name = event.target.value
+	}
+</script>
+
+<input value={name} on:input={onInput}>
+
+<h1>{name}!</h1>

test/js/samples/input-value/expected.js

@@ -12,6 +12,7 @@ import {
 	run_all,
 	safe_not_equal,
 	set_data,
+	set_input_value,
 	space,
 	text
 } from "svelte/internal";
@@ -169,6 +170,7 @@ function create_fragment(ctx) {
 		},
 		m(target, anchor) {
 			insert(target, input0, anchor);
+			set_input_value(input0, /*name*/ ctx[0]);
 			insert(target, t0, anchor);
 			insert(target, input1, anchor);
 			insert(target, t1, anchor);

test/js/samples/select-dynamic-value/expected.js

@@ -8,7 +8,8 @@ import {
 	insert,
 	noop,
 	safe_not_equal,
-	select_option
+	select_option,
+	set_input_value
 } from "svelte/internal";
 
 function create_fragment(ctx) {
@@ -31,7 +32,10 @@ function create_fragment(ctx) {
 		m(target, anchor) {
 			insert(target, select, anchor);
 			append(select, option0);
+			set_input_value(option0, "1");
 			append(select, option1);
+			set_input_value(option1, "2");
+			set_input_value(select, /*current*/ ctx[0]);
 			select_option(select, /*current*/ ctx[0]);
 		},
 		p(ctx, [dirty]) {