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/**
* Supports pseudo-"namespacing" for window-posted messages for a given test
* by generating and using a unique prefix that gets wrapped into message
* objects. This makes it more feasible to have multiple tests that use
* `window.postMessage` in a single test file. Basically, make it possible
* for the each test to listen for only the messages that are pertinent to it.
*
* 'Prefix' not an elegant term to use here but this models itself after
* PrefixedLocalStorage.
*
* PrefixedMessageTest: Instantiate in testharness.js tests to generate
* a new unique-ish prefix that can be used by other test support files
* PrefixedMessageResource: Instantiate in supporting test resource
* files to use/share a prefix generated by a test.
*/
var PrefixedMessage = function () {
this.prefix = '';
this.param = 'prefixedMessage'; // Param to use in querystrings
};
/**
* Generate a URL that adds/replaces param with this object's prefix
* Use to link to test support files that make use of
* PrefixedMessageResource.
*/
PrefixedMessage.prototype.url = function (uri) {
function updateUrlParameter (uri, key, value) {
var i = uri.indexOf('#');
var hash = (i === -1) ? '' : uri.substr(i);
uri = (i === -1) ? uri : uri.substr(0, i);
var re = new RegExp(`([?&])${key}=.*?(&|$)`, 'i');
var separator = uri.indexOf('?') !== -1 ? '&' : '?';
uri = (uri.match(re)) ? uri.replace(re, `$1${key}=${value}$2`) :
`${uri}${separator}${key}=${value}`;
return uri + hash;
}
return updateUrlParameter(uri, this.param, this.prefix);
};
/**
* Add an eventListener on `message` but only invoke the given callback
* for messages whose object contains this object's prefix. Remove the
* event listener once the anticipated message has been received.
*/
PrefixedMessage.prototype.onMessage = function (fn) {
window.addEventListener('message', e => {
if (typeof e.data === 'object' && e.data.hasOwnProperty('prefix')) {
if (e.data.prefix === this.prefix) {
// Only invoke callback when `data` is an object containing
// a `prefix` key with this object's prefix value
// Note fn is invoked with "unwrapped" data first, then the event `e`
// (which contains the full, wrapped e.data should it be needed)
fn.call(this, e.data.data, e);
window.removeEventListener('message', fn);
}
}
});
};
/**
* Instantiate in a test file (e.g. during `setup`) to create a unique-ish
* prefix that can be shared by support files
*/
var PrefixedMessageTest = function () {
PrefixedMessage.call(this);
this.prefix = `${document.location.pathname}-${Math.random()}-${Date.now()}-`;
};
PrefixedMessageTest.prototype = Object.create(PrefixedMessage.prototype);
PrefixedMessageTest.prototype.constructor = PrefixedMessageTest;
/**
* Instantiate in a test support script to use a "prefix" generated by a
* PrefixedMessageTest in a controlling test file. It will look for
* the prefix in a URL param (see also PrefixedMessage#url)
*/
var PrefixedMessageResource = function () {
PrefixedMessage.call(this);
// Check URL querystring for prefix to use
var regex = new RegExp(`[?&]${this.param}(=([^&#]*)|&|#|$)`),
results = regex.exec(document.location.href);
if (results && results[2]) {
this.prefix = results[2];
}
};
PrefixedMessageResource.prototype = Object.create(PrefixedMessage.prototype);
PrefixedMessageResource.prototype.constructor = PrefixedMessageResource;
/**
* This is how a test resource document can "send info" to its
* opener context. It will whatever message is being sent (`data`) in
* an object that injects the prefix.
*/
PrefixedMessageResource.prototype.postToOpener = function (data) {
if (window.opener) {
window.opener.postMessage({
prefix: this.prefix,
data: data
}, '*');
}
};