File size: 11,747 Bytes
979bf48
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
"use strict";
Object.defineProperty(exports, "__esModule", {
    value: true
});
0 && (module.exports = {
    IDLE_LINK_STATUS: null,
    PENDING_LINK_STATUS: null,
    mountFormInstance: null,
    mountLinkInstance: null,
    onLinkVisibilityChanged: null,
    onNavigationIntent: null,
    pingVisibleLinks: null,
    setLinkForCurrentNavigation: null,
    unmountLinkForCurrentNavigation: null,
    unmountPrefetchableInstance: null
});
function _export(target, all) {
    for(var name in all)Object.defineProperty(target, name, {
        enumerable: true,
        get: all[name]
    });
}
_export(exports, {
    IDLE_LINK_STATUS: function() {
        return IDLE_LINK_STATUS;
    },
    PENDING_LINK_STATUS: function() {
        return PENDING_LINK_STATUS;
    },
    mountFormInstance: function() {
        return mountFormInstance;
    },
    mountLinkInstance: function() {
        return mountLinkInstance;
    },
    onLinkVisibilityChanged: function() {
        return onLinkVisibilityChanged;
    },
    onNavigationIntent: function() {
        return onNavigationIntent;
    },
    pingVisibleLinks: function() {
        return pingVisibleLinks;
    },
    setLinkForCurrentNavigation: function() {
        return setLinkForCurrentNavigation;
    },
    unmountLinkForCurrentNavigation: function() {
        return unmountLinkForCurrentNavigation;
    },
    unmountPrefetchableInstance: function() {
        return unmountPrefetchableInstance;
    }
});
const _types = require("./segment-cache/types");
const _cachekey = require("./segment-cache/cache-key");
const _scheduler = require("./segment-cache/scheduler");
const _react = require("react");
// Tracks the most recently navigated link instance. When null, indicates
// the current navigation was not initiated by a link click.
let linkForMostRecentNavigation = null;
const PENDING_LINK_STATUS = {
    pending: true
};
const IDLE_LINK_STATUS = {
    pending: false
};
function setLinkForCurrentNavigation(link) {
    (0, _react.startTransition)(()=>{
        linkForMostRecentNavigation?.setOptimisticLinkStatus(IDLE_LINK_STATUS);
        link?.setOptimisticLinkStatus(PENDING_LINK_STATUS);
        linkForMostRecentNavigation = link;
    });
}
function unmountLinkForCurrentNavigation(link) {
    if (linkForMostRecentNavigation === link) {
        linkForMostRecentNavigation = null;
    }
}
// Use a WeakMap to associate a Link instance with its DOM element. This is
// used by the IntersectionObserver to track the link's visibility.
const prefetchable = typeof WeakMap === 'function' ? new WeakMap() : new Map();
// A Set of the currently visible links. We re-prefetch visible links after a
// cache invalidation, or when the current URL changes. It's a separate data
// structure from the WeakMap above because only the visible links need to
// be enumerated.
const prefetchableAndVisible = new Set();
// A single IntersectionObserver instance shared by all <Link> components.
const observer = typeof IntersectionObserver === 'function' ? new IntersectionObserver(handleIntersect, {
    rootMargin: '200px'
}) : null;
function observeVisibility(element, instance) {
    const existingInstance = prefetchable.get(element);
    if (existingInstance !== undefined) {
        // This shouldn't happen because each <Link> component should have its own
        // anchor tag instance, but it's defensive coding to avoid a memory leak in
        // case there's a logical error somewhere else.
        unmountPrefetchableInstance(element);
    }
    // Only track prefetchable links that have a valid prefetch URL
    prefetchable.set(element, instance);
    if (observer !== null) {
        observer.observe(element);
    }
}
function coercePrefetchableUrl(href) {
    if (typeof window !== 'undefined') {
        const { createPrefetchURL } = require('./app-router-utils');
        try {
            return createPrefetchURL(href);
        } catch  {
            // createPrefetchURL sometimes throws an error if an invalid URL is
            // provided, though I'm not sure if it's actually necessary.
            // TODO: Consider removing the throw from the inner function, or change it
            // to reportError. Or maybe the error isn't even necessary for automatic
            // prefetches, just navigations.
            const reportErrorFn = typeof reportError === 'function' ? reportError : console.error;
            reportErrorFn(`Cannot prefetch '${href}' because it cannot be converted to a URL.`);
            return null;
        }
    } else {
        return null;
    }
}
function mountLinkInstance(element, href, router, fetchStrategy, prefetchEnabled, setOptimisticLinkStatus) {
    if (prefetchEnabled) {
        const prefetchURL = coercePrefetchableUrl(href);
        if (prefetchURL !== null) {
            const instance = {
                router,
                fetchStrategy,
                isVisible: false,
                prefetchTask: null,
                prefetchHref: prefetchURL.href,
                setOptimisticLinkStatus
            };
            // We only observe the link's visibility if it's prefetchable. For
            // example, this excludes links to external URLs.
            observeVisibility(element, instance);
            return instance;
        }
    }
    // If the link is not prefetchable, we still create an instance so we can
    // track its optimistic state (i.e. useLinkStatus).
    const instance = {
        router,
        fetchStrategy,
        isVisible: false,
        prefetchTask: null,
        prefetchHref: null,
        setOptimisticLinkStatus
    };
    return instance;
}
function mountFormInstance(element, href, router, fetchStrategy) {
    const prefetchURL = coercePrefetchableUrl(href);
    if (prefetchURL === null) {
        // This href is not prefetchable, so we don't track it.
        // TODO: We currently observe/unobserve a form every time its href changes.
        // For Links, this isn't a big deal because the href doesn't usually change,
        // but for forms it's extremely common. We should optimize this.
        return;
    }
    const instance = {
        router,
        fetchStrategy,
        isVisible: false,
        prefetchTask: null,
        prefetchHref: prefetchURL.href,
        setOptimisticLinkStatus: null
    };
    observeVisibility(element, instance);
}
function unmountPrefetchableInstance(element) {
    const instance = prefetchable.get(element);
    if (instance !== undefined) {
        prefetchable.delete(element);
        prefetchableAndVisible.delete(instance);
        const prefetchTask = instance.prefetchTask;
        if (prefetchTask !== null) {
            (0, _scheduler.cancelPrefetchTask)(prefetchTask);
        }
    }
    if (observer !== null) {
        observer.unobserve(element);
    }
}
function handleIntersect(entries) {
    for (const entry of entries){
        // Some extremely old browsers or polyfills don't reliably support
        // isIntersecting so we check intersectionRatio instead. (Do we care? Not
        // really. But whatever this is fine.)
        const isVisible = entry.intersectionRatio > 0;
        onLinkVisibilityChanged(entry.target, isVisible);
    }
}
function onLinkVisibilityChanged(element, isVisible) {
    if (process.env.NODE_ENV !== 'production') {
        // Prefetching on viewport is disabled in development for performance
        // reasons, because it requires compiling the target page.
        // TODO: Investigate re-enabling this.
        return;
    }
    const instance = prefetchable.get(element);
    if (instance === undefined) {
        return;
    }
    instance.isVisible = isVisible;
    if (isVisible) {
        prefetchableAndVisible.add(instance);
    } else {
        prefetchableAndVisible.delete(instance);
    }
    rescheduleLinkPrefetch(instance, _types.PrefetchPriority.Default);
}
function onNavigationIntent(element, unstable_upgradeToDynamicPrefetch) {
    const instance = prefetchable.get(element);
    if (instance === undefined) {
        return;
    }
    // Prefetch the link on hover/touchstart.
    if (instance !== undefined) {
        if (process.env.__NEXT_DYNAMIC_ON_HOVER && unstable_upgradeToDynamicPrefetch) {
            // Switch to a full prefetch
            instance.fetchStrategy = _types.FetchStrategy.Full;
        }
        rescheduleLinkPrefetch(instance, _types.PrefetchPriority.Intent);
    }
}
function rescheduleLinkPrefetch(instance, priority) {
    // Ensures that app-router-instance is not compiled in the server bundle
    if (typeof window !== 'undefined') {
        const existingPrefetchTask = instance.prefetchTask;
        if (!instance.isVisible) {
            // Cancel any in-progress prefetch task. (If it already finished then this
            // is a no-op.)
            if (existingPrefetchTask !== null) {
                (0, _scheduler.cancelPrefetchTask)(existingPrefetchTask);
            }
            // We don't need to reset the prefetchTask to null upon cancellation; an
            // old task object can be rescheduled with reschedulePrefetchTask. This is a
            // micro-optimization but also makes the code simpler (don't need to
            // worry about whether an old task object is stale).
            return;
        }
        const { getCurrentAppRouterState } = require('./app-router-instance');
        const appRouterState = getCurrentAppRouterState();
        if (appRouterState !== null) {
            const treeAtTimeOfPrefetch = appRouterState.tree;
            if (existingPrefetchTask === null) {
                // Initiate a prefetch task.
                const nextUrl = appRouterState.nextUrl;
                const cacheKey = (0, _cachekey.createCacheKey)(instance.prefetchHref, nextUrl);
                instance.prefetchTask = (0, _scheduler.schedulePrefetchTask)(cacheKey, treeAtTimeOfPrefetch, instance.fetchStrategy, priority, null);
            } else {
                // We already have an old task object that we can reschedule. This is
                // effectively the same as canceling the old task and creating a new one.
                (0, _scheduler.reschedulePrefetchTask)(existingPrefetchTask, treeAtTimeOfPrefetch, instance.fetchStrategy, priority);
            }
        }
    }
}
function pingVisibleLinks(nextUrl, tree) {
    // For each currently visible link, cancel the existing prefetch task (if it
    // exists) and schedule a new one. This is effectively the same as if all the
    // visible links left and then re-entered the viewport.
    //
    // This is called when the Next-Url or the base tree changes, since those
    // may affect the result of a prefetch task. It's also called after a
    // cache invalidation.
    for (const instance of prefetchableAndVisible){
        const task = instance.prefetchTask;
        if (task !== null && !(0, _scheduler.isPrefetchTaskDirty)(task, nextUrl, tree)) {
            continue;
        }
        // Something changed. Cancel the existing prefetch task and schedule a
        // new one.
        if (task !== null) {
            (0, _scheduler.cancelPrefetchTask)(task);
        }
        const cacheKey = (0, _cachekey.createCacheKey)(instance.prefetchHref, nextUrl);
        instance.prefetchTask = (0, _scheduler.schedulePrefetchTask)(cacheKey, tree, instance.fetchStrategy, _types.PrefetchPriority.Default, null);
    }
}

if ((typeof exports.default === 'function' || (typeof exports.default === 'object' && exports.default !== null)) && typeof exports.default.__esModule === 'undefined') {
  Object.defineProperty(exports.default, '__esModule', { value: true });
  Object.assign(exports.default, exports);
  module.exports = exports.default;
}

//# sourceMappingURL=links.js.map