// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/**
* @fileoverview Leftover "cr." library functions to support some legacy
* JavaScript users. Do not use this file in new code.
*/
import {assertNotReached} from '//resources/ash/common/assert.js';
/**
* Dispatches a simple event on an event target.
* @param {!EventTarget} target The event target to dispatch the event on.
* @param {string} type The type of the event.
* @param {boolean=} bubbles Whether the event bubbles or not.
* @param {boolean=} cancelable Whether the default action of the event
* can be prevented. Default is true.
* @return {boolean} If any of the listeners called {@code preventDefault}
* during the dispatch this will return false.
*/
export function dispatchSimpleEvent(target, type, bubbles, cancelable) {
const e = new Event(
type,
{bubbles: bubbles, cancelable: cancelable === undefined || cancelable});
return target.dispatchEvent(e);
}
/**
* Fires a property change event on the target.
* @param {!EventTarget} target The target to dispatch the event on.
* @param {string} propertyName The name of the property that changed.
* @param {*} newValue The new value for the property.
* @param {*} oldValue The old value for the property.
*/
export function dispatchPropertyChange(
target, propertyName, newValue, oldValue) {
const e = new Event(propertyName + 'Change');
e.propertyName = propertyName;
e.newValue = newValue;
e.oldValue = oldValue;
target.dispatchEvent(e);
}
/**
* Converts a camelCase javascript property name to a hyphenated-lower-case
* attribute name.
* @param {string} jsName The javascript camelCase property name.
* @return {string} The equivalent hyphenated-lower-case attribute name.
*/
function getAttributeName(jsName) {
return jsName.replace(/([A-Z])/g, '-$1').toLowerCase();
}
/**
* The kind of property to define in {@code getPropertyDescriptor}.
* @enum {string}
* @const
*/
export const PropertyKind = {
/**
* Plain old JS property where the backing data is stored as a "private"
* field on the object.
* Use for properties of any type. Type will not be checked.
*/
JS: 'js',
/**
* The property backing data is stored as an attribute on an element.
* Use only for properties of type {string}.
*/
ATTR: 'attr',
/**
* The property backing data is stored as an attribute on an element. If the
* element has the attribute then the value is true.
* Use only for properties of type {boolean}.
*/
BOOL_ATTR: 'boolAttr',
};
/**
* Helper function for getPropertyDescriptor that returns the getter to use for
* the property.
* @param {string} name The name of the property.
* @param {PropertyKind} kind The kind of the property.
* @return {function():*} The getter for the property.
*/
function getGetter(name, kind) {
let attributeName;
switch (kind) {
case PropertyKind.JS:
const privateName = name + '_';
return function() {
return this[privateName];
};
case PropertyKind.ATTR:
attributeName = getAttributeName(name);
return function() {
return this.getAttribute(attributeName);
};
case PropertyKind.BOOL_ATTR:
attributeName = getAttributeName(name);
return function() {
return this.hasAttribute(attributeName);
};
}
assertNotReached();
}
/**
* Helper function for getPropertyDescriptor that returns the setter of the
* right kind.
* @param {string} name The name of the property we are defining the setter
* for.
* @param {PropertyKind} kind The kind of property we are getting the
* setter for.
* @param {function(*, *):void=} setHook A function to run after the
* property is set, but before the propertyChange event is fired.
* @return {function(*):void} The function to use as a setter.
*/
function getSetter(name, kind, setHook) {
let attributeName;
switch (kind) {
case PropertyKind.JS:
const privateName = name + '_';
return function(value) {
const oldValue = this[name];
if (value !== oldValue) {
this[privateName] = value;
if (setHook) {
setHook.call(this, value, oldValue);
}
dispatchPropertyChange(this, name, value, oldValue);
}
};
case PropertyKind.ATTR:
attributeName = getAttributeName(name);
return function(value) {
const oldValue = this[name];
if (value !== oldValue) {
if (value === undefined) {
this.removeAttribute(attributeName);
} else {
this.setAttribute(attributeName, value);
}
if (setHook) {
setHook.call(this, value, oldValue);
}
dispatchPropertyChange(this, name, value, oldValue);
}
};
case PropertyKind.BOOL_ATTR:
attributeName = getAttributeName(name);
return function(value) {
const oldValue = this[name];
if (value !== oldValue) {
if (value) {
this.setAttribute(attributeName, name);
} else {
this.removeAttribute(attributeName);
}
if (setHook) {
setHook.call(this, value, oldValue);
}
dispatchPropertyChange(this, name, value, oldValue);
}
};
}
assertNotReached();
}
/**
* Returns a getter and setter to be used as property descriptor in
* Object.defineProperty(). When the setter changes the value a property change
* event with the type {@code name + 'Change'} is fired.
* @param {string} name The name of the property.
* @param {PropertyKind=} kind What kind of underlying storage to use.
* @param {function(?, ?):void=} setHook A function to run after the
* property is set, but before the propertyChange event is fired.
*/
export function getPropertyDescriptor(name, kind = PropertyKind.JS, setHook) {
return {
get: getGetter(name, kind),
set: getSetter(name, kind, setHook),
};
}
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