Create cache key by run-length encoding statics

Prefix the key with a non-numeric character, as this seems to give a
speed-up on Chrome.

Author: jviide

src/index.mjs

@@ -16,7 +16,8 @@ const CACHE = {};
 const stringify = JSON.stringify;
 
 export default function html(statics) {
-	const key = stringify(statics);
+	let key = '.';
+	for (let i=0; i<statics.length; i++) key += statics[i].length + ',' + statics[i];
 	const tpl = CACHE[key] || (CACHE[key] = build(statics));
 
 	// eslint-disable-next-line prefer-rest-params

test/index.test.mjs

@@ -164,5 +164,7 @@ describe('htm', () => {
 	test('cache key should be unique', () => {
 		html`<a b="${'foo'}" />`;
 		expect(html`<a b="\0" />`).toEqual(h('a', { b: '\0' }));
+		expect(html`<a>${''}9aaaaaaaaa${''}</a>`).not.toEqual(html`<a>${''}0${''}aaaaaaaaa${''}</a>`);
+		expect(html`<a>${''}0${''}aaaaaaaa${''}</a>`).not.toEqual(html`<a>${''}.8aaaaaaaa${''}</a>`);
 	});
 });