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Core: cache refererInfo as long as location does not change #9670

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merged 1 commit into from
Apr 4, 2023
Merged

Core: cache refererInfo as long as location does not change #9670

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60 changes: 39 additions & 21 deletions src/refererDetection.js
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Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,26 @@ export function parseDomain(url, {noLeadingWww = false, noPort = false} = {}) {
return url;
}

/**
* This function returns canonical URL which refers to an HTML link element, with the attribute of rel="canonical", found in the <head> element of your webpage
*
* @param {Object} doc document
* @returns {string|null}
*/
function getCanonicalUrl(doc) {
try {
const element = doc.querySelector("link[rel='canonical']");

if (element !== null) {
return element.href;
}
} catch (e) {
// Ignore error
}

return null;
}

/**
* @param {Window} win Window
* @returns {Function}
Expand All @@ -75,26 +95,6 @@ export function detectReferer(win) {
}
}

/**
* This function returns canonical URL which refers to an HTML link element, with the attribute of rel="canonical", found in the <head> element of your webpage
*
* @param {Object} doc document
* @returns {string|null}
*/
function getCanonicalUrl(doc) {
try {
const element = doc.querySelector("link[rel='canonical']");

if (element !== null) {
return element.href;
}
} catch (e) {
// Ignore error
}

return null;
}

// TODO: the meaning of "reachedTop" seems to be intentionally ambiguous - best to leave them out of
// the typedef for now. (for example, unit tests enforce that "reachedTop" should be false in some situations where we
// happily provide a location for the top).
Expand Down Expand Up @@ -260,7 +260,25 @@ export function detectReferer(win) {
return refererInfo;
}

// cache result of fn (= referer info) as long as:
// - we are the top window
// - canonical URL tag and window location have not changed
export function cacheWithLocation(fn, win = window) {
if (win.top !== win) return fn;
let canonical, href, value;
return function () {
const newCanonical = getCanonicalUrl(win.document);
const newHref = win.location.href;
if (canonical !== newCanonical || newHref !== href) {
canonical = newCanonical;
href = newHref;
value = fn();
}
return value;
}
}

/**
* @type {function(): refererInfo}
*/
export const getRefererInfo = detectReferer(window);
export const getRefererInfo = cacheWithLocation(detectReferer(window));
57 changes: 56 additions & 1 deletion test/spec/refererDetection_spec.js
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
import {detectReferer, ensureProtocol, parseDomain} from 'src/refererDetection.js';
import {cacheWithLocation, detectReferer, ensureProtocol, parseDomain} from 'src/refererDetection.js';
import {config} from 'src/config.js';
import {expect} from 'chai';

Expand Down Expand Up @@ -493,3 +493,58 @@ describe('parseDomain', () => {
})
})
});

describe('cacheWithLocation', () => {
let fn, win, cached;
const RESULT = 'result';
beforeEach(() => {
fn = sinon.stub().callsFake(() => RESULT);
win = {
location: {
},
document: {
querySelector: sinon.stub()
}
}
});

describe('when window is not on top', () => {
beforeEach(() => {
win.top = {};
cached = cacheWithLocation(fn, win);
})

it('should not cache', () => {
win.top = {};
cached();
expect(cached()).to.eql(RESULT);
expect(fn.callCount).to.eql(2);
});
})

describe('when window is on top', () => {
beforeEach(() => {
win.top = win;
cached = cacheWithLocation(fn, win);
})

it('should not cache when canonical URL changes', () => {
let canonical = 'foo';
win.document.querySelector.callsFake(() => ({href: canonical}));
cached();
expect(cached()).to.eql(RESULT);
canonical = 'bar';
expect(cached()).to.eql(RESULT);
expect(fn.callCount).to.eql(2);
});

it('should not cache when location changes', () => {
win.location.href = 'foo';
cached();
expect(cached()).to.eql(RESULT);
win.location.href = 'bar';
expect(cached()).to.eql(RESULT);
expect(fn.callCount).to.eql(2);
})
});
})