theinvensi/pagedjs-repeat-table-header.js

## pagedjs-repeat-table-header.js
class RepeatTableHeadersHandler extends Paged.Handler {
    constructor(chunker, polisher, caller) {
        super(chunker, polisher, caller)
        this.splitTablesRefs = []
    }

    afterPageLayout(pageElement, page, breakToken, chunker) {
        this.chunker = chunker
        this.splitTablesRefs = []

        if (breakToken) {
            const node = breakToken.node
            const tables = this.findAllAncestors(node, "table")
            if (node.tagName === "TABLE") tables.push(node)

            if (tables.length > 0) {
                this.splitTablesRefs = tables.map(t => t.dataset.ref)

                let thead = node.tagName === "THEAD" ? node : this.findFirstAncestor(node, "thead")
                if (thead) {
                    let lastTheadNode = thead.hasChildNodes() ? thead.lastChild : thead
                    breakToken.node = this.nodeAfter(lastTheadNode, chunker.source)
                }

                this.hideEmptyTables(pageElement, node)
            }
        }
    }

    hideEmptyTables(pageElement, breakTokenNode) {
        this.splitTablesRefs.forEach(ref => {
            let table = pageElement.querySelector("[data-ref='" + ref + "']")
            if (table) {
                let sourceBody = table.querySelector("tbody > tr")
                if (!sourceBody || this.refEquals(sourceBody.firstElementChild, breakTokenNode)) {
                    table.style.visibility = "hidden"
                    table.style.position = "absolute"
                    let lineSpacer = table.nextSibling
                    if (lineSpacer) {
                        lineSpacer.style.visibility = "hidden"
                        lineSpacer.style.position = "absolute"
                    }
                }
            }
        })
    }

    refEquals(a, b) {
        return a && a.dataset && b && b.dataset && a.dataset.ref === b.dataset.ref
    }

    findFirstAncestor(element, selector) {
        while (element.parentNode && element.parentNode.nodeType === 1) {
            if (element.parentNode.matches(selector)) return element.parentNode
            element = element.parentNode
        }
        return null
    }

    findAllAncestors(element, selector) {
        const ancestors = []
        while (element.parentNode && element.parentNode.nodeType === 1) {
            if (element.parentNode.matches(selector)) ancestors.unshift(element.parentNode)
            element = element.parentNode
        }
        return ancestors
    }

    layout(rendered, layout) {
        this.splitTablesRefs.forEach(ref => {
            const renderedTable = rendered.querySelector("[data-ref='" + ref + "']")
            if (renderedTable) {
                if (!renderedTable.getAttribute("repeated-headers")) {
                    const sourceTable = this.chunker.source.querySelector("[data-ref='" + ref + "']")
                    this.repeatColgroup(sourceTable, renderedTable)
                    this.repeatTHead(sourceTable, renderedTable)
                    renderedTable.setAttribute("repeated-headers", true)
                }
            }
        })
    }

    repeatColgroup(sourceTable, renderedTable) {
        let colgroup = sourceTable.querySelectorAll("colgroup")
        let firstChild = renderedTable.firstChild
        colgroup.forEach((colgroup) => {
            let clonedColgroup = colgroup.cloneNode(true)
            renderedTable.insertBefore(clonedColgroup, firstChild)
        })
    }

    repeatTHead(sourceTable, renderedTable) {
        let thead = sourceTable.querySelector("thead")
        if (thead) {
            let clonedThead = thead.cloneNode(true)
            renderedTable.insertBefore(clonedThead, renderedTable.firstChild)
        }
    }

    nodeAfter(node, limiter) {
        if (limiter && node === limiter) return
        let significantNode = this.nextSignificantNode(node)
        if (significantNode) return significantNode
        if (node.parentNode) {
            while ((node = node.parentNode)) {
                if (limiter && node === limiter) return
                significantNode = this.nextSignificantNode(node)
                if (significantNode) return significantNode
            }
        }
    }

    nextSignificantNode(sib) {
        while ((sib = sib.nextSibling)) { if (!this.isIgnorable(sib)) return sib }
        return null
    }

    isIgnorable(node) {
        return (
            (node.nodeType === 8)
            || ((node.nodeType === 3) && this.isAllWhitespace(node))
        )
    }

    isAllWhitespace(node) {
        return !(/[^\t\n\r ]/.test(node.textContent))
    }
}

Paged.registerHandlers(RepeatTableHeadersHandler)