angular-docs-cn/packages/zone.js/lib/browser/define-property.ts

117 lines
3.8 KiB
TypeScript

/**
* @license
* Copyright Google Inc. All Rights Reserved.
*
* Use of this source code is governed by an MIT-style license that can be
* found in the LICENSE file at https://angular.io/license
*/
/*
* This is necessary for Chrome and Chrome mobile, to enable
* things like redefining `createdCallback` on an element.
*/
let zoneSymbol: any;
let _defineProperty: any;
let _getOwnPropertyDescriptor: any;
let _create: any;
let unconfigurablesKey: any;
export function propertyPatch() {
zoneSymbol = Zone.__symbol__;
_defineProperty = (Object as any)[zoneSymbol('defineProperty')] = Object.defineProperty;
_getOwnPropertyDescriptor = (Object as any)[zoneSymbol('getOwnPropertyDescriptor')] =
Object.getOwnPropertyDescriptor;
_create = Object.create;
unconfigurablesKey = zoneSymbol('unconfigurables');
Object.defineProperty = function(obj: any, prop: string, desc: any) {
if (isUnconfigurable(obj, prop)) {
throw new TypeError('Cannot assign to read only property \'' + prop + '\' of ' + obj);
}
const originalConfigurableFlag = desc.configurable;
if (prop !== 'prototype') {
desc = rewriteDescriptor(obj, prop, desc);
}
return _tryDefineProperty(obj, prop, desc, originalConfigurableFlag);
};
Object.defineProperties = function(obj, props) {
Object.keys(props).forEach(function(prop) { Object.defineProperty(obj, prop, props[prop]); });
return obj;
};
Object.create = <any>function(obj: any, proto: any) {
if (typeof proto === 'object' && !Object.isFrozen(proto)) {
Object.keys(proto).forEach(function(prop) {
proto[prop] = rewriteDescriptor(obj, prop, proto[prop]);
});
}
return _create(obj, proto);
};
Object.getOwnPropertyDescriptor = function(obj, prop) {
const desc = _getOwnPropertyDescriptor(obj, prop);
if (desc && isUnconfigurable(obj, prop)) {
desc.configurable = false;
}
return desc;
};
}
export function _redefineProperty(obj: any, prop: string, desc: any) {
const originalConfigurableFlag = desc.configurable;
desc = rewriteDescriptor(obj, prop, desc);
return _tryDefineProperty(obj, prop, desc, originalConfigurableFlag);
}
function isUnconfigurable(obj: any, prop: any) {
return obj && obj[unconfigurablesKey] && obj[unconfigurablesKey][prop];
}
function rewriteDescriptor(obj: any, prop: string, desc: any) {
// issue-927, if the desc is frozen, don't try to change the desc
if (!Object.isFrozen(desc)) {
desc.configurable = true;
}
if (!desc.configurable) {
// issue-927, if the obj is frozen, don't try to set the desc to obj
if (!obj[unconfigurablesKey] && !Object.isFrozen(obj)) {
_defineProperty(obj, unconfigurablesKey, {writable: true, value: {}});
}
if (obj[unconfigurablesKey]) {
obj[unconfigurablesKey][prop] = true;
}
}
return desc;
}
function _tryDefineProperty(obj: any, prop: string, desc: any, originalConfigurableFlag: any) {
try {
return _defineProperty(obj, prop, desc);
} catch (error) {
if (desc.configurable) {
// In case of errors, when the configurable flag was likely set by rewriteDescriptor(), let's
// retry with the original flag value
if (typeof originalConfigurableFlag == 'undefined') {
delete desc.configurable;
} else {
desc.configurable = originalConfigurableFlag;
}
try {
return _defineProperty(obj, prop, desc);
} catch (error) {
let descJson: string|null = null;
try {
descJson = JSON.stringify(desc);
} catch (error) {
descJson = desc.toString();
}
console.log(`Attempting to configure '${prop}' with descriptor '${descJson}' on object '${
obj}' and got error, giving up: ${error}`);
}
} else {
throw error;
}
}
}