diff --git a/src/index.mjs b/src/index.mjs
index d8cbe639..0c81ea9a 100644
--- a/src/index.mjs
+++ b/src/index.mjs
@@ -111,6 +111,9 @@ export function listen(options = {}) {
const delay = options.delay || 0;
const hrefsInViewport = new Map();
const specRulesInViewport = new Map();
+ // Prefetches handed to the throttler that haven't started yet. `toPrefetch`
+ // only grows once a task runs, so queued work has to be reserved separately.
+ let scheduled = 0;
const timeoutFn = options.timeoutFn || requestIdleCallback;
const hrefFn = typeof options.hrefFn === 'function' && options.hrefFn;
@@ -174,8 +177,10 @@ export function listen(options = {}) {
}
// Do not prefetch if will match/exceed limit and user has not switched to shouldOnlyPrerender mode
- if (toPrefetch.size < limit && !shouldOnlyPrerender) {
+ if (toPrefetch.size + scheduled < limit && !shouldOnlyPrerender) {
+ scheduled++;
toAdd(() => {
+ scheduled--;
prefetch(
hrefFn ? hrefFn(entry) : entry.href,
options.priority,
diff --git a/test/fixtures/test-limit-throttle.html b/test/fixtures/test-limit-throttle.html
new file mode 100644
index 00000000..02ff55bc
--- /dev/null
+++ b/test/fixtures/test-limit-throttle.html
@@ -0,0 +1,25 @@
+
+
+
+
+
+ Prefetch: Limit and throttle
+
+
+
+
+
+ Link 1
+ Link 2
+ Link 3
+ Link 4
+
+
+
+
+
diff --git a/test/quicklink.spec.js b/test/quicklink.spec.js
index 72b0f5d9..19d2d2aa 100644
--- a/test/quicklink.spec.js
+++ b/test/quicklink.spec.js
@@ -317,6 +317,24 @@ mainSuite('should not exceed the `limit` total', async context => {
assert.ok(ours.includes(`${server}/1.html`));
});
+mainSuite('should not exceed the `limit` when `throttle` is also set', async context => {
+ const URLs = [];
+
+ context.handleRequest = async req => {
+ const url = req.url();
+ if (/test\/fixtures\/\d+\.html$/i.test(url)) {
+ URLs.push(url);
+ return req.respond({status: 200});
+ }
+
+ return req.continue();
+ };
+
+ await context.page.goto(`${server}/test-limit-throttle.html`);
+ await sleep();
+ assert.is(URLs.length, 2);
+});
+
mainSuite('should respect the `throttle` concurrency', async context => {
const URLs = []; // Note: Page makes 4 requests