I made this for my simple text editor.
Differences from other methods:
- High performance
- Works with all spaces
usage
// get current selection
const [start, end] = getSelectionOffset(container)
// change container html
container.innerHTML = newHtml
// restore selection
setSelectionOffset(container, start, end)
// use this instead innerText for get text with keep all spaces
const innerText = getInnerText(container)
const textBeforeCaret = innerText.substring(0, start)
const textAfterCaret = innerText.substring(start)
selection.ts
/** return true if node found */
function searchNode(
container: Node,
startNode: Node,
predicate: (node: Node) => boolean,
excludeSibling?: boolean,
): boolean {
if (predicate(startNode as Text)) {
return true
}
for (let i = 0, len = startNode.childNodes.length; i < len; i++) {
if (searchNode(startNode, startNode.childNodes[i], predicate, true)) {
return true
}
}
if (!excludeSibling) {
let parentNode = startNode
while (parentNode && parentNode !== container) {
let nextSibling = parentNode.nextSibling
while (nextSibling) {
if (searchNode(container, nextSibling, predicate, true)) {
return true
}
nextSibling = nextSibling.nextSibling
}
parentNode = parentNode.parentNode
}
}
return false
}
function createRange(container: Node, start: number, end: number): Range {
let startNode
searchNode(container, container, node => {
if (node.nodeType === Node.TEXT_NODE) {
const dataLength = (node as Text).data.length
if (start <= dataLength) {
startNode = node
return true
}
start -= dataLength
end -= dataLength
return false
}
})
let endNode
if (startNode) {
searchNode(container, startNode, node => {
if (node.nodeType === Node.TEXT_NODE) {
const dataLength = (node as Text).data.length
if (end <= dataLength) {
endNode = node
return true
}
end -= dataLength
return false
}
})
}
const range = document.createRange()
if (startNode) {
if (start < startNode.data.length) {
range.setStart(startNode, start)
} else {
range.setStartAfter(startNode)
}
} else {
if (start === 0) {
range.setStart(container, 0)
} else {
range.setStartAfter(container)
}
}
if (endNode) {
if (end < endNode.data.length) {
range.setEnd(endNode, end)
} else {
range.setEndAfter(endNode)
}
} else {
if (end === 0) {
range.setEnd(container, 0)
} else {
range.setEndAfter(container)
}
}
return range
}
export function setSelectionOffset(node: Node, start: number, end: number) {
const range = createRange(node, start, end)
const selection = window.getSelection()
selection.removeAllRanges()
selection.addRange(range)
}
function hasChild(container: Node, node: Node): boolean {
while (node) {
if (node === container) {
return true
}
node = node.parentNode
}
return false
}
function getAbsoluteOffset(container: Node, offset: number) {
if (container.nodeType === Node.TEXT_NODE) {
return offset
}
let absoluteOffset = 0
for (let i = 0, len = Math.min(container.childNodes.length, offset); i < len; i++) {
const childNode = container.childNodes[i]
searchNode(childNode, childNode, node => {
if (node.nodeType === Node.TEXT_NODE) {
absoluteOffset += (node as Text).data.length
}
return false
})
}
return absoluteOffset
}
export function getSelectionOffset(container: Node): [number, number] {
let start = 0
let end = 0
const selection = window.getSelection()
for (let i = 0, len = selection.rangeCount; i < len; i++) {
const range = selection.getRangeAt(i)
if (range.intersectsNode(container)) {
const startNode = range.startContainer
searchNode(container, container, node => {
if (startNode === node) {
start += getAbsoluteOffset(node, range.startOffset)
return true
}
const dataLength = node.nodeType === Node.TEXT_NODE
? (node as Text).data.length
: 0
start += dataLength
end += dataLength
return false
})
const endNode = range.endContainer
searchNode(container, startNode, node => {
if (endNode === node) {
end += getAbsoluteOffset(node, range.endOffset)
return true
}
const dataLength = node.nodeType === Node.TEXT_NODE
? (node as Text).data.length
: 0
end += dataLength
return false
})
break
}
}
return [start, end]
}
export function getInnerText(container: Node) {
const buffer = []
searchNode(container, container, node => {
if (node.nodeType === Node.TEXT_NODE) {
buffer.push((node as Text).data)
}
return false
})
return buffer.join('')
}
