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node_modules/lit-html/node/development/directives/live.js

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+import { noChange, nothing } from '../lit-html.js';
+import { directive, Directive, PartType } from '../directive.js';
+import { isSingleExpression, setCommittedValue } from '../directive-helpers.js';
+
+/**
+ * @license
+ * Copyright 2020 Google LLC
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+class LiveDirective extends Directive {
+    constructor(partInfo) {
+        super(partInfo);
+        if (!(partInfo.type === PartType.PROPERTY ||
+            partInfo.type === PartType.ATTRIBUTE ||
+            partInfo.type === PartType.BOOLEAN_ATTRIBUTE)) {
+            throw new Error('The `live` directive is not allowed on child or event bindings');
+        }
+        if (!isSingleExpression(partInfo)) {
+            throw new Error('`live` bindings can only contain a single expression');
+        }
+    }
+    render(value) {
+        return value;
+    }
+    update(part, [value]) {
+        if (value === noChange || value === nothing) {
+            return value;
+        }
+        const element = part.element;
+        const name = part.name;
+        if (part.type === PartType.PROPERTY) {
+            // eslint-disable-next-line @typescript-eslint/no-explicit-any
+            if (value === element[name]) {
+                return noChange;
+            }
+        }
+        else if (part.type === PartType.BOOLEAN_ATTRIBUTE) {
+            if (!!value === element.hasAttribute(name)) {
+                return noChange;
+            }
+        }
+        else if (part.type === PartType.ATTRIBUTE) {
+            if (element.getAttribute(name) === String(value)) {
+                return noChange;
+            }
+        }
+        // Resets the part's value, causing its dirty-check to fail so that it
+        // always sets the value.
+        setCommittedValue(part);
+        return value;
+    }
+}
+/**
+ * Checks binding values against live DOM values, instead of previously bound
+ * values, when determining whether to update the value.
+ *
+ * This is useful for cases where the DOM value may change from outside of
+ * lit-html, such as with a binding to an `<input>` element's `value` property,
+ * a content editable elements text, or to a custom element that changes it's
+ * own properties or attributes.
+ *
+ * In these cases if the DOM value changes, but the value set through lit-html
+ * bindings hasn't, lit-html won't know to update the DOM value and will leave
+ * it alone. If this is not what you want--if you want to overwrite the DOM
+ * value with the bound value no matter what--use the `live()` directive:
+ *
+ * ```js
+ * html`<input .value=${live(x)}>`
+ * ```
+ *
+ * `live()` performs a strict equality check against the live DOM value, and if
+ * the new value is equal to the live value, does nothing. This means that
+ * `live()` should not be used when the binding will cause a type conversion. If
+ * you use `live()` with an attribute binding, make sure that only strings are
+ * passed in, or the binding will update every render.
+ */
+const live = directive(LiveDirective);
+
+export { live };
+//# sourceMappingURL=live.js.map