import { parse } from 'parse5';
import { createElement, getTagName, appendChild, findElement } from '@web/parse5-utils';

const doc = parse(`
  <html>
    <body>
      <my-element></my-element>
      <div id="foo"></div>
    </body>
  </html>`);

const body = findElement(doc, e => getTagName(e) === 'body');
const script = createElement('script', { src: './foo.js' });
appendChild(body, script);

import { parse } from 'parse5';
import { getTagName, getAttribute, findElements } from '@web/parse5-utils';

const doc = parse(`
  <html>
    <body>
      <script src="./a.js"></script>
      <script type="module" src="./b.js"></script>
      <script type="module" src="./c.js"></script>
    </body>
  </html>`);

const allModuleScripts = findElements(
  doc,
  e => getTagName(e) === 'script' && getAttribute(e, 'type') === 'module',
);

appendToDocument and prependToDocument will inject a snippet of HTML into the page, making sure it is executed last or first respectively.

It tries to avoid changing the formatting of the original file, using parse5 to find out the location of body and head tags and string concatenation in the original code to do the actual injection. In case of incomplete or invalid HTML it may fall back parse5 to generate a valid document and inject using AST manipulation.

import { prependToDocument, appendToDocument } from '@web/parse5-utils';

const html = '<html><body></body></html>';
const htmlWithInjectedScript = appendToDocument(
  html,
  '<scrip type="module" src="./injected-script.js"></script>',
);

Available functions

createDocument
createDocumentFragment
createElement
createScript
createCommentNode
appendChild
insertBefore
setTemplateContent
getTemplateContent
setDocumentType
setDocumentMode
getDocumentMode
detachNode
insertText
insertTextBefore
adoptAttributes
getFirstChild
getChildNodes
getParentNode
getAttrList
getTagName
getNamespaceURI
getTextNodeContent
getCommentNodeContent
getDocumentTypeNodeName
getDocumentTypeNodePublicId
getDocumentTypeNodeSystemId
isTextNode
isCommentNode
isDocumentTypeNode
isElementNode
setNodeSourceCodeLocation
getNodeSourceCodeLocation
updateNodeSourceCodeLocation
isHtmlFragment
hasAttribute
getAttribute
getAttributes
setAttribute
setAttributes
removeAttribute
setTextContent
getTextContent
remove
findNode
findNodes
findElement
findElements
prepend
prependToDocument
appendToDocument

Keywords

FAQs

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Package last updated on 20 Jan 2026

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