Set-based alternative to #3979

src/create-context.js

@@ -19,13 +19,13 @@ export function createContext(defaultValue, contextId) {
 		Provider(props) {
 			if (!this.getChildContext) {
 				/** @type {import('./internal').Component[]} */
-				let subs = [];
+				let subs = new Set();
 				let ctx = {};
 				ctx[contextId] = this;
 
 				this.getChildContext = () => ctx;
 
-				this.shouldComponentUpdate = function (_props) {
+				this.shouldComponentUpdate = function(_props) {
 					if (this.props.value !== _props.value) {
 						// I think the forced value propagation here was only needed when `options.debounceRendering` was being bypassed:
 						// https://github.com/preactjs/preact/commit/4d339fb803bea09e9f198abf38ca1bf8ea4b7771#diff-54682ce380935a717e41b8bfc54737f6R358
@@ -41,18 +41,18 @@ export function createContext(defaultValue, contextId) {
 						// 	c.context[contextId] = _props.value;
 						// 	enqueueRender(c);
 						// });
-						subs.some(c => {
+						subs.forEach(c => {
 							c._force = true;
 							enqueueRender(c);
 						});
 					}
 				};
 
 				this.sub = c => {
-					subs.push(c);
+					subs.add(c);
 					let old = c.componentWillUnmount;
 					c.componentWillUnmount = () => {
-						subs.splice(subs.indexOf(c), 1);
+						subs.delete(c);
 						if (old) old.call(c);
 					};
 				};
@@ -68,6 +68,5 @@ export function createContext(defaultValue, contextId) {
 	// of on the component itself. See:
 	// https://reactjs.org/docs/context.html#contextdisplayname
 
-	return (context.Provider._contextRef = context.Consumer.contextType =
-		context);
+	return (context.Provider._contextRef = context.Consumer.contextType = context);
 }