135 lines
3.6 KiB
TypeScript
135 lines
3.6 KiB
TypeScript
export class Diff {
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static persistentClasses = new Set<string>()
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static persistentAttributes = new Set<string>()
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// Reuse container for diffs to avoid memory allocation
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static container: HTMLElement
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static rootContainer: HTMLElement
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// innerHTML will diff the element with the given HTML string and apply DOM mutations.
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static innerHTML(aRoot: HTMLElement, html: string) {
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if(!Diff.container) {
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Diff.container = document.createElement("main")
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}
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Diff.container.innerHTML = html
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Diff.childNodes(aRoot, Diff.container)
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}
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// root will diff the document root element with the given HTML string and apply DOM mutations.
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static root(aRoot: HTMLElement, html: string) {
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if(!Diff.rootContainer) {
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Diff.rootContainer = document.createElement("html")
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}
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Diff.rootContainer.innerHTML = html.replace("<!DOCTYPE html>", "")
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Diff.childNodes(aRoot.getElementsByTagName("body")[0], Diff.rootContainer.getElementsByTagName("body")[0])
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}
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// childNodes diffs the child nodes of 2 given elements and applies DOM mutations.
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static childNodes(aRoot: Node, bRoot: Node) {
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let aChild = [...aRoot.childNodes]
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let bChild = [...bRoot.childNodes]
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let numNodes = Math.max(aChild.length, bChild.length)
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for(let i = 0; i < numNodes; i++) {
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let a = aChild[i]
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// Remove nodes at the end of a that do not exist in b
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if(i >= bChild.length) {
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aRoot.removeChild(a)
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continue
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}
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let b = bChild[i]
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// If a doesn't have that many nodes, simply append at the end of a
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if(i >= aChild.length) {
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aRoot.appendChild(b)
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continue
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}
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// If it's a completely different HTML tag or node type, replace it
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if(a.nodeName !== b.nodeName || a.nodeType !== b.nodeType) {
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aRoot.replaceChild(b, a)
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continue
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}
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// Text node:
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// We don't need to check for b to be a text node as well because
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// we eliminated different node types in the previous condition.
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if(a.nodeType === Node.TEXT_NODE) {
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a.textContent = b.textContent
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continue
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}
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// HTML element:
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if(a.nodeType === Node.ELEMENT_NODE) {
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let elemA = a as HTMLElement
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let elemB = b as HTMLElement
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let removeAttributes: Attr[] = []
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for(let x = 0; x < elemA.attributes.length; x++) {
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let attrib = elemA.attributes[x]
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if(attrib.specified) {
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if(!elemB.hasAttribute(attrib.name) && !Diff.persistentAttributes.has(attrib.name)) {
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removeAttributes.push(attrib)
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}
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}
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}
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for(let attr of removeAttributes) {
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elemA.removeAttributeNode(attr)
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}
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for(let x = 0; x < elemB.attributes.length; x++) {
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let attrib = elemB.attributes[x]
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if(!attrib.specified) {
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continue
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}
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// If the attribute value is exactly the same, skip this attribute.
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if(elemA.getAttribute(attrib.name) === attrib.value) {
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continue
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}
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if(attrib.name === "class") {
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let classesA = elemA.classList
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let classesB = elemB.classList
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let removeClasses: string[] = []
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for(let className of classesA) {
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if(!classesB.contains(className) && !Diff.persistentClasses.has(className)) {
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removeClasses.push(className)
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}
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}
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for(let className of removeClasses) {
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classesA.remove(className)
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}
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for(let className of classesB) {
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if(!classesA.contains(className)) {
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classesA.add(className)
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}
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}
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continue
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}
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elemA.setAttribute(attrib.name, attrib.value)
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}
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// Special case: Apply state of input elements
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if(elemA !== document.activeElement && elemA instanceof HTMLInputElement && elemB instanceof HTMLInputElement) {
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elemA.value = elemB.value
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}
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}
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Diff.childNodes(a, b)
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}
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}
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} |