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sliceChildren.js
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49 lines (44 loc) · 1.29 KB
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/**
* Copyright 2013-2014, 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 sliceChildren
*/
"use strict";
var flattenChildren = require('flattenChildren');
/**
* Slice children that are typically specified as `props.children`. This version
* of slice children ignores empty child components.
*
* @param {*} children The children set to filter.
* @param {number} start The first zero-based index to include in the subset.
* @param {?number} end The non-inclusive last index of the subset.
* @return {object} mirrored array with mapped children
*/
function sliceChildren(children, start, end) {
if (children == null) {
return children;
}
var slicedChildren = {};
var flattenedMap = flattenChildren(children);
var ii = 0;
for (var key in flattenedMap) {
if (!flattenedMap.hasOwnProperty(key)) {
continue;
}
var child = flattenedMap[key];
if (ii >= start) {
slicedChildren[key] = child;
}
ii++;
if (end != null && ii >= end) {
break;
}
}
return slicedChildren;
}
module.exports = sliceChildren;