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/**
* Copyright 2013-present, 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.
*
*/
'use strict';
/**
* Given any node return the first leaf node without children.
*
* @param {DOMElement|DOMTextNode} node
* @return {DOMElement|DOMTextNode}
*/
function getLeafNode(node) {
while (node && node.firstChild) {
node = node.firstChild;
}
return node;
}
/**
* Get the next sibling within a container. This will walk up the
* DOM if a node's siblings have been exhausted.
*
* @param {DOMElement|DOMTextNode} node
* @return {?DOMElement|DOMTextNode}
*/
function getSiblingNode(node) {
while (node) {
if (node.nextSibling) {
return node.nextSibling;
}
node = node.parentNode;
}
}
/**
* Get object describing the nodes which contain characters at offset.
*
* @param {DOMElement|DOMTextNode} root
* @param {number} offset
* @return {?object}
*/
function getNodeForCharacterOffset(root, offset) {
var node = getLeafNode(root);
var nodeStart = 0;
var nodeEnd = 0;
while (node) {
if (node.nodeType === 3) {
nodeEnd = nodeStart + node.textContent.length;
if (nodeStart <= offset && nodeEnd >= offset) {
return {
node: node,
offset: offset - nodeStart
};
}
nodeStart = nodeEnd;
}
node = getLeafNode(getSiblingNode(node));
}
}
module.exports = getNodeForCharacterOffset;
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