How to get the entire document HTML as a string?

Question

Is there a way in JS to get the entire HTML within the html tags, as a string?

document.documentElement.??

Answer 1

To also get things outside the ..., most importantly the declaration, you could walk through document.childNodes, turning each into a string:

const html = [...document.childNodes]
    .map(node => nodeToString(node))
    .join('\n') // could use '' instead, but whitespace should not matter.

function nodeToString(node) {
    switch (node.nodeType) {
        case node.ELEMENT_NODE:
            return node.outerHTML
        case node.TEXT_NODE:
            // Text nodes should probably never be encountered, but handling them anyway.
            return node.textContent
        case node.COMMENT_NODE:
            return ``
        case node.DOCUMENT_TYPE_NODE:
            return doctypeToString(node)
        default:
            throw new TypeError(`Unexpected node type: ${node.nodeType}`)
    }
}

I published this code as document-outerhtml on npm.

---

edit Note the code above depends on a function doctypeToString; its implementation could be as follows (code below is published on npm as doctype-to-string):

function doctypeToString(doctype) {
    if (doctype === null) {
        return ''
    }
    // Checking with instanceof DocumentType might be neater, but how to get a
    // reference to DocumentType without assuming it to be available globally?
    // To play nice with custom DOM implementations, we resort to duck-typing.
    if (!doctype
        || doctype.nodeType !== doctype.DOCUMENT_TYPE_NODE
        || typeof doctype.name !== 'string'
        || typeof doctype.publicId !== 'string'
        || typeof doctype.systemId !== 'string'
    ) {
        throw new TypeError('Expected a DocumentType')
    }
    const doctypeString = ``
    return doctypeString
}