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ReactEmptyComponent.js
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80 lines (68 loc) · 2.27 KB
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/**
* Copyright 2014, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
* @providesModule ReactEmptyComponent
*/
"use strict";
var ReactElement = require('ReactElement');
var ReactInstanceMap = require('ReactInstanceMap');
var invariant = require('invariant');
var component;
// This registry keeps track of the React IDs of the components that rendered to
// `null` (in reality a placeholder such as `noscript`)
var nullComponentIdsRegistry = {};
var ReactEmptyComponentInjection = {
injectEmptyComponent: function(emptyComponent) {
component = ReactElement.createFactory(emptyComponent);
}
};
var ReactEmptyComponentType = function() {};
ReactEmptyComponentType.prototype.componentDidMount = function() {
var internalInstance = ReactInstanceMap.get(this);
registerNullComponentID(internalInstance._rootNodeID);
};
ReactEmptyComponentType.prototype.componentWillUnmount = function() {
var internalInstance = ReactInstanceMap.get(this);
deregisterNullComponentID(internalInstance._rootNodeID);
};
ReactEmptyComponentType.prototype.render = function() {
invariant(
component,
'Trying to return null from a render, but no null placeholder component ' +
'was injected.'
);
return component();
};
var emptyElement = ReactElement.createElement(ReactEmptyComponentType);
/**
* Mark the component as having rendered to null.
* @param {string} id Component's `_rootNodeID`.
*/
function registerNullComponentID(id) {
nullComponentIdsRegistry[id] = true;
}
/**
* Unmark the component as having rendered to null: it renders to something now.
* @param {string} id Component's `_rootNodeID`.
*/
function deregisterNullComponentID(id) {
delete nullComponentIdsRegistry[id];
}
/**
* @param {string} id Component's `_rootNodeID`.
* @return {boolean} True if the component is rendered to null.
*/
function isNullComponentID(id) {
return !!nullComponentIdsRegistry[id];
}
var ReactEmptyComponent = {
emptyElement: emptyElement,
injection: ReactEmptyComponentInjection,
isNullComponentID: isNullComponentID
};
module.exports = ReactEmptyComponent;